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1.
In this study we report the levels of 3-methoxy-4-hydroxyphenylglycol, 3,4-dihydroxyphenylacetic acid, homovallinic acid, tryptophan, 5-hydroxyindole-3-acetic acid and serotonin in lumbar cerebrospinal fluid (CSF) from patients with multiple sclerosis, cerebrovascular disease and muscular tension headache the later, as healthy controls. The separation of these substances was performed on a reversed phase column by ion pair high performance liquid chromatography and detection was made by a glassy carbon electrode set at +900 mV vs Ag+/AgCl. The whole separation was achieved within 25 min. Concentrations of all substances (10-1000 pmole/L) were linearly proportional to areas obtained. The system is sensitive, stable and reproducible. The significance of CSF levels of these metabolites from patients groups compared with healthy controls are discussed. 相似文献
2.
I. H. Qureshi M. S. Chaudhary S. Ahmad 《Journal of Radioanalytical and Nuclear Chemistry》1982,68(1-2):209-218
Instrumental neutron activation analysis technique has been used to determine the concentration levels of 12 trace elements
in human head hair samples collected from 105 individuals living in various areas of Rawalpindi-Islamabad. The data show that
the average concentrations of Mn, Co, Ag and Au are higher in the female group as compared to the male group. Four individuals
were found to have elevated levels of Se due to the use of anti-dandruff shampoos, whereas two individials had elevated levels
of Hg. 相似文献
3.
M. S. Chaudhary S. Ahmad A. Mannan I. H. Qureshi 《Journal of Radioanalytical and Nuclear Chemistry》1984,83(2):387-396
An instrumental neutron activation analytical (INAA) technique is described for the determination of 26 toxic and other trace elements in Eastern Coal (NBS SRM-1632a), local coal and its ash. The coal ash was produced by heating coal at 750°C in a muffled furnace. The transfer of these elements to the environment on the complete compustion of coal is estimated from the difference between the elemental concentration of coal and its ash. 相似文献
4.
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
5.
Summary HPCL quantitation of piperine in pepper and in pepper extracts is described. This is optimised on nitratedsulphonated phenyl silica gel with phloracetophenone as internal standard. 相似文献
6.
S. Ahmad M. S. Chaudhary A. Mannan I. H. Qureshi 《Journal of Radioanalytical and Nuclear Chemistry》1983,78(2):375-383
The concentration of certain toxic and essential elements in various brands of tea consumed locally were determined using instrumental neutron activation analysis. Transference of these elements into the drinkable portion was studied by brewing and boiling tea leaves for two minutes and the approximate intake was calculated from this data. The toxic effects of Hg, Se, As, Br and Sb are briefly discussed. 相似文献
7.
J. H. Zaidi I. Fatima M. Arif I. H. Qureshi 《Journal of Radioanalytical and Nuclear Chemistry》2005,267(1):109-112
Summary Extensive use of coffee, by one-third of world's population, entails the evaluation of trace element contents in it. Instrumental
neutron activation analysis (INAA) was successfully employed to determine the concentration of 20 trace elements (essential,
toxic and nonessential) in four samples of coffee beans of various origins and two instant coffee brands most commonly consumed
in Pakistan. This study provides the base-line values of certain toxic and essential elements in coffee. The daily intake
of essential and toxic elements through coffee was estimated and compared with the recommended values. The cumulative intake
of Mn is four times higher than the recommended value and that of toxic elements is well below the tolerance limits. 相似文献
8.
The high TC
superconducting phase Bi2Sr2Ca2Cu3Ox
(2223) in the Pb-BSCCO system has been produced by EDTA-gel processing
using nitrate solutions. The precursor has heated in two stages, at 300 and
800°C each for 2 h, to avoid the burning of the important species involved
in the final product. The effects of time (6 to 48 h) and temperature (845
and 855°C) on the formation of the 2223 phase have been studied by sintering
the samples in air. Thermal analysis (TG/DTA), X-ray diffraction (XRD), scanning
electron microscopy (SEM) and a vibrating sample magnetometer (VSM) have been
employed to investigate the powder produced at different stages of decomposition,
oxidation and formation of sintered materials from the powders. The volume-fraction
of the 2223 phase at 845°C increases with time, the maximum value of the
2223 phase was obtained at 120 h. It has been observed that the formation
of the high TC phase
is remarkably enhanced at the temperature of the endothermic peak of the DTA
curve. The best result has been obtained in the sample sintered for 24 h at
the temperature 855°C (endothermic peak). This also indicated that at
855°C, the large volume-fraction of 2223 phase with TC
113 K grew in short time and as the sintering time increased, it decomposed
into the Bi2Sr2CaCu2Ox
(2212) phase and other phases. 相似文献
9.
Erik Larsen Abdel Aleem H. Abdel Aleem Erik B. Pedersen 《Journal of heterocyclic chemistry》1995,32(5):1645-1646
α-Thymidine (4) was synthesized from thymidine (1) in 3 steps in 36% overall yield without using chro-matography and with the possibility of increasing the yield to 85% by reusing the remaining α,β-mixture. 1-(2-Deoxy-3,5-di-O-p-toluoyl-α-D-erythro-pentofuranosyl)thymine (3) was further converted to 1-(2-deoxy-α-D-erythro-pentofuranosyl)-5-methylcytosine (5) . 相似文献
10.
The extraction of PAN chelates of the group IB, IIB and IIIA–VA elements from aqueous solutions of pH 1–10 into chloroform
has been studied radiochemically. Re-extraction studies have been made to strip the metal ions from the organic phase into
aqueous solutions of KCN, HClO4 and buffer solutions. The effects of certain masking agents on the extraction of these elements have also been studied. The
extraction curves indicate the possibilities of devising group chemical separation procedures for use in activation analysis. 相似文献