Elevation of intracellular cyclic adenosine 3',5'-monophosphate levels in macrophages activated with lipopolysaccharide for tumor cell killing.

The macrophage activation for tumor cytotoxicity with lipopolysaccharide (LPS) was remarkably inhibited by adding indomethacin (5 x 10(-6) M) or 10mM LiCl which is known to inhibit adenylate cyclase activity. The tumor cytotoxicity of macrophages inhibited with these agents was recovered by adding dibutyryl cyclic adenosine 3',5'-monophosphate (cAMP) (10(-4) or 10(-5) M) and furthermore tumor cell killing activity was augmented as compared with LPS-activated macrophage. Macrophages showed a 5 to 6 times increased intracellular cAMP concentration over the control within 30 min when incubated with LPS. However, the increased intracellular cAMP concentration was decreased by adding LiCl (10 mM). Thus, these findings indicate that there is an important relation between intracellular cAMP concentration and the mechanism of macrophage activation. One can then conclude that at least the initial enhancement of intracellular cAMP was important for tumor cell killing as a signal transmission in macrophage activated by LPS.     

Simultaneous polarographic determination of adenosine-5'-monophosphate and adenosine-5'-0-monothiophosphate at the nanogram level.

A method is described for the simultaneous gas Chromatographie determination of arsenic, germanium and antimony. The approach is based on conversion of the elements to their hydrides, collection of these via a semi-selective trapping procedure, desorption from the trap, and delivery to a gas Chromatograph for separation and determination. Detection limits, based on the analysis of 100-ml natural water samples, are 1, 0.3, and 10 μg l^-1 for As, Ge, and Sb, respectively. Recovery studies indicate that the relatively simple method yields precise and accurate results.     

Intracellular adenosine 5'-triphosphate, adenosine 5'-diphosphate, and adenosine 5'-monophosphate detection by short-end injection capillary electrophoresis using methylcellulose as the effective electroosmostic flow suppressor

We present a new rapid CE method to measure adenine nucleotides adenosine 5'-triphosphate (ATP), adenosine 5'-diphosphate (ADP), and adenosine 5'-monophosphate (AMP) in cells. The short-end injection mode allows a decrease in the analysis time by injecting samples at the outlet end of a silica capillary closest to the detection window, reducing the migration distance. Moreover, the use of methylcellulose (MC) as run buffer additive to suppress EOF permits to further reduce the migration times of analytes. Thus, when a capillary with an effective length of 10.2 cm was used with a 60 mmol/L sodium acetate buffer pH 3.80 in the presence of 0.01% of MC, the migration time of analytes were 1.35 min for ATP, 1.85 min for ADP, and 4.64 min for AMP. These conditions gave a good reproducibility for intra- and interassay (CV <4 and 8%, respectively) and all the procedure demonstrated an excellent analytical recovery (from 98.3 to 99 %). The method suitability was proved both on red blood cells and in spermatozoa. We compared our proposed method to a spectrophotometric assay, by measuring ATP levels in 40 spermatozoa samples. The obtained data were analyzed by the Passing and Bablok regression and Bland-Altman test.     

Rapid automated high-performance liquid chromatographic analysis of cyclic adenosine 3',5'-monophosphate. Synthesis in brain tissues

A rapid and sensitive automated system for measuring cyclic adenosine 3',5'-monophosphate (cAMP) synthesized from either radiolabelled adenine or adenosine 5'-triphosphate (ATP) in intact and broken cell tissue preparations, respectively, is described. After incubation with radiolabelled precursor, tissue samples are deproteinized and then injected directly onto a reversed-phase high-performance liquid chromatographic column. The column effluent fraction which contains cAMP is collected into scintillation vials and assayed for tritium by liquid scintillation spectrometry. Since the high-performance liquid chromatographic and fraction collection procedures are automated, over fifty samples can be analyzed in duplicate in a single day. The utility of this assay is illustrated by investigations of the effects of beta-adrenergic receptor stimulation on cAMP synthesis in tissue slices prepared from rat cerebral cortex and dopamine on cAMP synthesis in striatal membrane preparations.     

Complexation of thallium(I) with adenosine 5'-monophosphate in aqueous methanol solutions.

The formation constants of the species formed in the systems H+ + thallium(I) + AMP and H+ + AMP have been determined in aqueous solutions of methanol at 25 degrees C and constant ionic strength 0.1 mol dm(-3) sodium perchlorate, using spectrophotometric and potentiometric techniques. Thallium(I) forms two mononuclear 1:1 complexes with AMP of the type TlHL and TlL- in the pH range of study (1-11), where L2- represents the fully dissociated ligand. The formation constants in various media were analyzed in terms of Kamlet and Taft's parameters. Single-parameter correlation of the formation constants, beta111, and beta101, versus alpha (hydrogen-bond donor acidity), beta (hydrogen-bond accepter basicity), and for pi* (dipolarity/polarizability) are relatively poor in all solutions, but multi-parameter correlation represents significant improvement with regard to the single-parameter models. Finally, the results are discussed in terms of the effect of the solvent on complexation.     

稀土元素对3'-腺嘌呤及3'-鸟嘌呤核苷酸的水解断裂作用

用核磁共振(NMR)波谱、HPLC和化学定磷法研究了稀土元素对3'-腺嘌呤核苷酸(3'-AMP)3及3'-鸟嘌呤核苷酸(3'-GMP)的水解断裂作用, 结果表明: 不同稀土元素对3'位核苷酸断裂有较强的特异性, 在37℃, pH9的条件下, 使3'-AMP断裂为腺嘌呤核苷(A)及无机磷, 使3'-GMP断裂为鸟嘌呤核苷(G)及无机磷, 其断裂作用远大于5'位核苷酸, 并对其水解断裂进行了研究。     

离子色谱法测定增味剂中的5′-肌苷酸二钠和5′-鸟苷酸二钠

 建立了增味剂中5′-肌苷酸二钠和5′-鸟苷酸二钠的离子色谱分析方法。采用lonPacASll阴离子交换色谱柱,以20mmol／LNa2CO3一体积分数为15％的甲醇溶液为淋洗液,检测波长254um。方法已用于实际样品的测定。     

Trinuclear copper(II) complex showing high selectivity for the hydrolysis of 2'-5' over 3'-5' for UpU and 3'-5' over 2'-5' for ApA ribonucleotides

The cooperative action of multiple Cu(II) nuclear centers is shown to be effective and selective in the hydrolysis of 2'-5' and 3'-5' ribonucleotides. Reported herein is the specific catalysis by two trinuclear Cu(II) complexes of L3A and L3B. Pseudo first-order kinetic studies reveal that the L3A trinuclear Cu(II) complex effects hydrolysis of Up(2'-5')U with a rate constant of 28 x 10(-)(4) min(-)(1) and Up(3'-5')U with a rate constant of 0.5 x 10(-)(4) min(-)(1). The hydrolyses of Ap(3'-5')A and Ap(2'-5')A proceed with rate constants of 24 x 10(-)(4) min(-)(1) and 0.5 x 10(-)(4) min(-)(1) respectively. The L3A trinuclear Cu(II) complex demonstrates high specificity for Up(2'-5')U and Ap(3'-5')A. Similar studies with the more rigid L3B trinuclear Cu(II) complex shows no selectivity and yields lower rate constants for hydrolysis. The selectivity observed with the L3A ligand is attributed to the geometry of the ligand-bound diribonucleotide which ultimately dictates the proximity of the attacking hydroxyl and the phosphoester to a Cu(II) center for activation and subsequent hydrolysis.