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Shah BH Siddiqui A Qureshi KA Khan M Rafi S Ujan VA Yakoob MY Yaqub Y Rasheed H Saeed SA 《Experimental & molecular medicine》1999,31(1):42-46
Our previous studies have shown that subthreshold concentrations of two platelet agonists exert synergistic effects on platelet aggregation. Here we studied the mechanism of synergistic interaction of 5-hydroxytryptamine (5-HT) and epinephrine mediated platelet aggregation. We show that 5-HT had no or little effect on aggregation but it did potentiate the aggregation response of epinephrine. The synergistic interaction of 5-HT (1-5 microM) and epinephrine (0.5-2 microM) was inhibited by alpha2-adrenoceptor blocker (yohimbine; IC50= 0.4 microM), calcium channel blockers (verapamil and diltiazem with IC50 of 10 and 48 mM, respectively), PLC inhibitor (U73122; IC50=6 microM) and nitric oxide (NO) donor, SNAP (IC50=1.6 microM)). The data suggest that synergistic effects of platelet agonists are receptor-mediated and occur through multiple signalling pathways including the activation PLC/Ca2+ signalling cascades. 相似文献
4.
The thermal stability of the Schiff base ethylacetoacetate-o-chlorobenzylamine (bdII), N-o-chlorobenzyl-C-benzoyl acetamide (bdIII), and N-p-chlorobenzyl-C-benzoyl acetamide (bdIV) were studied by thermogravimetric analysis. II Gave N,N'-di(o-chlorobenzyl) urea (bdIa) at 60° C, whereas the thermogravimetric curves of III and IV indicate that reactions other than formation of I may occur. The urea derivatives (I) have also been prepared from benzylamines and the corresponding β-ketoester and identified. 相似文献
5.
Aamer Saeed 《Monatshefte für Chemie / Chemical Monthly》2003,134(3):457-463
Summary. A short facile synthesis of the fungal metabolite (±)-3,4-dihydro-3,6,8-trihydroxy-3- pentadecylisocoumarin (peniolactol)
has been achieved. Condensation of hexadecanoyl chloride with 3,5-dimethoxyhomophthalic acid afforded 6,8-dimethoxy-3-pentadecylisocoumarin,
which on sequential saponification and demethylation furnished rac-peniolactol in 31% overall yield. The ring-chain tautomerism was studied in solution by 1H NMR and the mass fragmentation pattern. 3-Pentadecyl- isocoumarin was also synthesized and saponified to the corresponding
keto acid as a model compound for comparative studies.
E-mail: aamersaeed@yahoo.com
Received May 23, 2002; accepted May 30, 2002 相似文献
6.
White-Morris RL Stender M Tinti DS Balch AL Rios D Attar S 《Inorganic chemistry》2003,42(10):3237-3244
The preparation and X-ray crystal structures of (CyNC)Au(I)CN, (n-BuNC)Au(I)CN, and (i-PrNC)Au(I)CN.0.5CH(2)Cl(2) are reported and compared with those of (MeNC)Au(I)CN and (t-BuNC)Au(I)CN, which were previously described. These linear molecules are all organized through aurophilic interactions into three structural classes: simple chains ((CyNC)Au(I)CN and (t-BuNC)Au(I)CN), side-by-side chains in which two strands make Au...Au contact with each other ((n-BuNC)Au(I)CN), and nets in which multiple aurophilic interactions produce layers of gold(I) centers ((i-PrNC)Au(I)CN and (MeNC)Au(I)CN). All of these five solids dissolve to produce colorless, nonluminescent solutions with similar UV/vis spectra. However, each of the solids displays a unique luminescence with emission maxima occurring in the range 371-430 nm. 相似文献
7.
An isocratic ion-pair reversed-phase liquid chromatographic method has been developed for the determination of thirteen nucleotides including cyclic AMP and cyclic GMP. The resolution capability of this method was evaluated successfully using homogenates of octopus retina, the aim being to elucidate the role of nucleotides (particularly ADP and ATP) in the control of oxidative metabolism. To overcome the inherent lack of specificity of ultraviolet detection we used the coupling of liquid chromatography with mass spectrometry, via a thermospray interface, to confirm the identity of the nucleotides of interest in the biological samples. 相似文献
8.
M. N. Cheema M. Mufazzal Saeed Akbar Ali Munir Ahmed 《Journal of Radioanalytical and Nuclear Chemistry》1994,178(1):153-163
Extraction of Hg(II), Se(IV), Mn(II) and Co(II) has been carried out with 1-phenyl-3-methyl-4-trifluoroacetyl-2-pyrazolin-5-one (HPMTFP) and triphenylphosphine oxide (TPPO) into chloroform from pH 1–10. Quantitative extraction of Hg(II), Mn(II) and Co(II) at pH 4 with equimolar 0.05M (PMTFP+TPPO) in chloroform was observed. Se(IV) remains unextracted at this pH range. The stoichiometric composition of the extracted complexes M(PMTFP)2·nH2O (M=Mn, Hg), M(PMTFP)2·2TPPO (M=Mn and Co) and Co(PMTFP)2·TPPO·H2O at less than 0.1M TPPO has been established. The formation constantsK
m,0 andK
m,n and stability constants
m,n have been computed. The analytical method developed was applied to the IAEA standard reference material (SRM) potato fluor V-4 for the determination of these elements using NAA technique. 相似文献
9.
Aggregation and dispersion characteristics of calcium oxalate monohydrate: effect of urinary species
Christmas KG Gower LB Khan SR El-Shall H 《Journal of colloid and interface science》2002,256(1):168-174
In this research, screening and central composite experimental designs are used to determine the effect of various factors on the aggregation and dispersion characteristics of previously grown calcium oxalate monohydrate (COM) crystals in artificial urinary environments of controlled variables. The variables examined are pH and calcium, oxalate, pyrophosphate, citrate, and protein concentrations in ultrapure water and artificial urine. Optical density measurements, particle size analysis, optical microscopy, AFM force measurements, and protein adsorption have been used to assess the state of aggregation and dispersion of the COM crystals and to elucidate the mechanisms involved in such a complex system. The data indicate that our model protein, mucin, acts as a dispersant. This is attributed to steric hindrance resulting from the adsorbed mucoprotein. Oxalate, however, promotes aggregation. Interesting interactions between protein and oxalate along with protein and citrate are observed. Such interactions (synergistic or antagonistic) are found to depend on the concentrations of these species. Surface responses for these interactions are presented and discussed in this paper. In summary, solution, surface, and interface chemistries interact in a complex manner in the physiological environment to either inhibit or promote aggregation, and an understanding of such interactions may help determine and control the factors affecting kidney stone formation. 相似文献
10.
A new complex formulated as [Cu(Pn)2(N3)(BH4)](Pn = 1,3-propanediamine) has been prepared and characterized. The results indicate that the tetrahydroborate and azide ions complete the coordination. The complex is octahedral and non-electrolytic. A cyclic voltammetric study shows that the complex exhibits a single one-electron redox couple (Cu2+/Cu+). 相似文献