Immobilization of AMP-deaminase in acrylamide-glycidylmethacrylate copolymer

The enzyme AMP-deaminase was entrapped in an acrylamide-glycidylmethacrylate copolymer. No leakage of AMP-deaminase was observed from the copolymer. The optimum pH of native AMP-deaminase was 5.6. The pH was displaced to 5.0 with immobilization in the copolymer. The immobilized AMP-deaminase column maintained more than 95% of initial activity after 10 days of operation.     

A new method for the determination of adenine phosphoribosyltransferase activity in human erythrocytes by reversed phase high performance liquid chromatography

A new method for the determination of adenine phosphoribosyltransferase (APRT) activity in human erythrocytes is described. APRT activity was assayed by a non-radiochemical method in which adenosine monophosphate (AMP) and AMP metabolites produced from a substrate adenine were converted to inosine by alkaline phosphatase and adenosine deaminase. The inosine thus produced was quantitated by reversed phase HPLC. This method was simple, precise, sensitive and free from interference with other co-existing erythrocyte enzymes. Four patients with 2,8-dihydroxyadenine urolithiasis and others with several disorders in purine metabolism have been studied, showing that the present method is clinically useful for the diagnosis and the evaluation of the severity of some human diseases.     

Graves病患者经131I治疗后血浆和红细胞锌含量的变化及其临床意义

为研究Graves病(GD)患者经^131I治疗后血浆和红细胞锌(Zn)含量的变化及其临床意义，采用原子吸收分光光谱法(AAS)和放射免疫分析法(Rn)分别检测了40例GD患者、20例经^131I治疗后甲状腺功能恢复至正常水平GD患者与30名健康人血浆和红细胞Zn的含量以及血浆甲状腺激素水平。结果表明，GD组红细胞Zn含量明显低于对照组(P＜0．01)；血浆Zn含量虽略低于对照组，但无统计学意义(P＜0．05)；且Zn与FT4呈明显负相关(P＜0．01)、与TSH呈正相关(P＜0．05)。GD治疗缓解组红细胞Zn明显高于治疗前(P＜0．01)，血浆Zn明显低于治疗前(P＜0．05)；红细胞Zn检测GD的敏感性与特异性分别为95．0％与96．7％。提示GD患者存在红细胞Zn含量改变，甲状腺激素可能干扰红细胞Zn的代谢，同时测定红细胞Zn可作为GD的临床诊断、治疗以及疾病转归的参考指标。     

制备方法对Cr/Si-2催化剂在CO2氧化乙烷脱氢制乙烯反应中的催化性能的影响

采用直接水热合成法和浸渍法制备了相同Cr含量的Cr/Si-2催化剂,并在常压固定床微反应器上,考察了它们在CO2或者N2气氛下的乙烷脱氢制乙烯反应中的催化性能及稳定性.由于存在逆水煤气反应和Boudouard反应,CO2能显著促进乙烷的脱氢反应.不论是在CO2还是在N2气氛下,直接水热法制备的催化剂均比浸渍法制备的催化剂显示出更好的催化性能.高价态的Cr物种被认为是催化剂具有高活性的关键.在CO2气氛下的乙烷脱氢制乙烯反应中,浸渍法制备的催化剂比水热法制备的催化剂失活更快,催化剂失活速率的差异可能与它们的氧化还原性质有关.然而在N2气氛下的乙烷脱氢制乙烯反应中,这两种方法制备的催化剂失活速率差异不大.     

Investigation of elemental models in senile dementia and depressives using neutron activation analysis

Instrumental neutron activation analysis has been used to determine the concentration of a range of elements in hair and blood samples, separated into erythrocytes and plasma, obtained from two groups of women, senile demented (9) and depressives (16), and their respective controls (17 and 9). The results suggest that the senile dementia group has significantly higher Al concentrations in erythrocytes and hair relative to the controls but no significant correlation between the aluminium content of hair and that of blood exists. Further, Zn concentrations determined in the erythrocytes and plasma of these subjects were lower compared to the control values. Vanadium levels above our detection limit for the element were found in seven cases out of a total of sixteen in the depressive group. Vanadium was also found to be at higher concentration in the hair of the depressive group compared to the controls. Again no significant correlation was found to exist between the concentration of vanadium in hair and in erythrocyte sample for these seven subjects.     

Investigation of the role of electrolytes and non-electrolytes on the cloud point and dye solubilization in antidepressant drug imipramine hydrochloride solutions

Antidepressant drug imipramine hydrochloride (IMP) is amphiphilic which shows surfactant-like behavior in aqueous solutions. We have studied the effect of adding electrolytes and non-electrolytes on the micellar behavior of IMP by making cloud point (CP) and dye solubilization measurements. The CP of a 100mM IMP solution (prepared in 10mM sodium phosphate (SP) buffer) was found to decrease with increasing pH, both in the absence as well as presence of added salts. Increase in pH increased the visible absorbance of Sudan III dye solubilized in the drug micelles, implying micellar growth. Addition of increasing amounts of salts to 100mM IMP solutions (at pH 6.7) caused continuous increase in CP due to micellar growth. On the basis of these studies, the binding-effect orders of counter- and co-ions have been deduced, respectively, as: Br(-)>Cl(-)>F(-) and Li(+)相似文献   

制备方法对 Ni-Al2O3催化剂在 CO2-CH4重整反应中 催化性能的影响

为提高镍基催化剂的干法重整活性,采用溶液燃烧法、等体积浸渍法、胶体磨循环浸渍法和水热-沉积法制备了SCM、IMP、T310和HTP四种催化剂,在800 ℃考察了其在CO₂-CH₄重整反应中的催化性能,并结合ICP-AES、N₂吸附-脱附、XRD、H₂-TPR和TEM等表征手段对催化剂进行分析。结果表明,水热-沉积法和胶体磨循环浸渍法制备的催化剂比表面积较大,分别为190.83和182.21 m²/g,可为反应提供较多的接触面积,进而提高催化剂的初始活性(HTP试样CH₄和CO₂初始转化率相对较高,分别达85.15%和90.84%);而溶液燃烧法和等体积浸渍法制备的催化剂具有较多的NiAl₂O₄尖晶石,其还原峰面积占总还原峰面积90%以上,还原后可获得更多晶粒粒径更小的稳定活性组分Ni(SCM和IMP试样稳定性更好,反应50 h后活性超过HTP和T310试样,100 h后CH₄转化率方降至50%以下)。因此,决定催化剂稳定活性的更重要的因素应该是活性组分Ni晶粒粒径的大小及其抗烧结能力的强弱。     

Trace elements in sickle cell disease

Instrumental Neutron Activation Analysis (INAA) and Proton-Induced X-ray Emission (PIXE) analysis (employed as a complementary technique) have been used to determine the concentration of 11 elements in blood samples and its components erythrocytes and plasma obtained, from three groups of subjects in Nigeria viz: sickle cell anaemia (SCA) subjects, subjects with sickle cell trait and normal control subjects. The results suggest that SCA subjects have significantly higher concentrations of Na, Cl, Ca and Cu in their whole blood and erythrocytes and a higher concentration, of Cl and Cu in their plasma relative to the control subjects. Furthermore, a significantly lower concentration of K, Fe, Zn, Se, Br and Rb were found in the whole blood and erythrocytes of the SCA subjects as compared to the controls while the concentration of K and Fe in the plasma of the SCA subjects were however, found to be significantly higher than that of the control group. The study also shows that there was no significant differences between the concentration of these 11 elements in the group with sickle cell trait and the normal control group.     

Characterization of molecular weight distribution of oligomers from autocatalyzed batch hydrolysis of xylan

Oat spelt xylan was treated with water in a batch reactor at temperatures of 180 and 200°C. Ion-moderated partition (IMP) chromatography was then applied to separate oligomers in solution according to their molecular size. Calibration of the IMP measurements based on peak height was found to quantify dissolved monomer and oligomer yields well. Oligomer concentrations in the liquid hydrolysate were also determined from the difference in xylose monomer concentrations measured by high-performance liquid chromatography before and after posthydrolysis of dissolved xylooligosaccharides to xylose. Delayed formation and then rapid disappearance of oligomers from DP10 to DP2 was observed by IMP, and total oligomer yields measured by IMP and posthydrolysis were very similar at these times. However, while IMP detected virtually no oligomers initially, posthydrolysis measurements gave significant amounts of soluble oligomers at these times, indicating that oligomers with chain lengths >10 were in solution but not detectable by the IMP system used.     

The yeast <Emphasis Type="Italic">ISN1</Emphasis> (<Emphasis Type="Italic">YOR155c</Emphasis>) gene encodes a new type of IMP-specific 5'-nucleotidase

Background  

The purine salvage enzyme inosine 5'-monophosphate (IMP)-specific 5'-nucleotidase catalyzes degradation of IMP to inosine. Although this enzymatic activity has been purified and characterized in Saccharomyces cerevisiae, the gene encoding IMP 5'-nucleotidase had not been identified.     

Sensitive fluorimetric method for the determination of putrescine, spermidine and spermine by high-performance liquid chromatography and its application to human blood

A fast and sensitive method for the determination of putrescine, spermidine and spermine by high-performance liquid chromatography is described. These compounds are converted to their fluorescent dansyl derivatives and are separated by a reversed-phase chromatographic system (Micropak CH-10) with water and acetonitrile as mobile phase. The sensitivity of the method is 30 pmoles. The application of the method to the determination of polyamines in blood is described. It was found that most of the polyamines circulating in blood are localized in the erythrocytes, their content in normal human blood being spermidine 14.1 +/- 3.1, and spermine 8.4 +/- 2.8 nmoles/ml packed erythrocytes. The polyamine level in serum is less than 0.1 nmole/ml. The polyamine content of the erythrocytes from patients with malignant neoplasms was significantly elevated.     

固相萃取法对微量药物的选择性富集和直接测定

选用能够识别抗菌药物氧苄氨嘧啶（ＴＭＰ）的模权聚合物作固相萃取剂,从稀溶液中可选择性地富集ＴＭＰ,在生理浓度下,富集因数为３５．７,而非模板事物无富集能力。在洗脱过程中直接用于ＴＭＰ的测定,不需要随后的色谱分析手续。基于此,建立了一个样品富集和测定的新方法,方便简单可靠,用于尿样中低２的ＴＭＰ的测定,回收率达到９１．７％,结果满意。     

Electrochemical activity and morphology of human erythrocytes at optically transparent ITO electrode

The electrochemical activity of a suspension of human erythrocytes was found at potentials above +0.4 V. The limiting current of electrooxidation was found to linearly depend on the cell concentration in the suspension. The electrochemical activity of an erythrocyte suspension is accompanied by reversible changes in the cell morphology only in non-buffered media.     

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。     

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。     

Amperometric detection of uric acid and hypoxanthine with Xanthine oxidase immobilized and carbon based screen-printed electrode. Application for fish freshness determination

Carbon-based screen-printed electrodes are suitable for uric acid detection. Xanthine oxidase (XO) was immobilized either directly on the surface of the electrode or in a reactor with CPG aminopropylsilane in a FIA assembly. Higher reproducibility and lifetime was obtained with the reactor. Optimum conditions were found for the determination of Hypoxanthine (Hx), Inosine (HxR) and Inosine monophosphate (IMP). Calibration curves for IMP, HxR and Hx are linear up to 50 muM with detection limit of 1 muM for 50 mul injection. One assay is completed within 30 s. The reproducibility of 20 muM of Hx was obtained with CV 2%.     

Activity of membrane-bound NADH-methemoglobin reductase and physical state of lipids in erythrocyte membranes

The activity of membrane-bound NADH-methemoglobin reductase in erythrocytes and the physical state of lipids in erythrocyte membranes under oxidative stress in cells were studied. A decrease of the activity of membrane-bound NADH-methemoglobin reductase and a change of physical state of the lipid bilayer of membranes under oxidative stress were found in erythrocytes in vivo and in vitro.     

Effect of some trace elements on the nucleic acid metabolising enzymes level of germinating wheat seeds

Wheat seeds were grown in the presence and absence of some trace elements like Co, Cu, Fe, Mn, Mo and Zn in non-toxic limits. The level of enzyme activities involved in nucleic acid metabolism were measured by spectrophotometric methods. The level of certain RNA metabolising enzymes increased manyfold in trace element-treated seeds, while the level of AMP-deaminase was increased manyfold in Co-treated seeds.     

Identification of urinary metabolites of imperatorin with a single run on an LC/Triple TOF system based on multiple mass defect filter data acquisition and multiple data mining techniques

The detection of drug metabolites, especially for minor metabolites, continues to be a challenge because of the complexity of biological samples. Imperatorin (IMP) is an active natural furocoumarin component originating from many traditional Chinese herbal medicines and is expected to be pursued as a new vasorelaxant agent. In the present study, a generic and efficient approach was developed for the in vivo screening and identification of IMP metabolites using liquid chromatography-Triple TOF mass spectrometry. In this approach, a novel on-line data acquisition method mutiple mass defect filter (MMDF) combined with dynamic background subtraction was developed to trace all probable urinary metabolites of IMP. Comparing with the traditionally intensity-dependent data acquisition method, MMDF method could give the information of low-level metabolites masked by background noise and endogenous components. Thus, the minor metabolites in complex biological matrices could be detected. Then, the sensitive and specific multiple data-mining techniques extracted ion chromatography, mass defect filter, product ion filter, and neutral loss filter were used for the discovery of IMP metabolites. Based on the proposed strategy, 44 phase I and 7 phase II metabolites were identified in rat urine after oral administration of IMP. The results indicated that oxidization was the main metabolic pathway and that different oxidized substituent positions had a significant influence on the fragmentation of the metabolites. Two types of characteristic ions at m/z 203 and 219 can be observed in the MS/MS spectra. This is the first study of IMP metabolism in vivo. The interpretation of the MS/MS spectra of these metabolites and the proposed metabolite pathway provide essential data for further pharmacological studies of other linear-type furocoumarins.     

Iron(III) Located in the Dinuclear Metallo‐β‐Lactamase IMP‐1 by Pseudocontact Shifts

Heterodinuclear metalloenzymes are an important class of metalloproteins, but determining the location of the different metal ions can be difficult. Herein we present a new NMR spectroscopy method that uses pseudocontact shifts (PCS) to achieve this without assumptions about the coordinating ligands. The approach is illustrated with the dinuclear [FeZn] complex of IMP‐1, which is a prototypical metallo‐β‐lactamase (MβL) that confers resistance to β‐lactam antibiotics. Results from single‐crystal X‐ray diffraction were compromised by degradation during crystallization. With [GaZn]‐IMP‐1 as diamagnetic reference, the PCSs unambiguously identified the iron binding site in fresh samples of [FeZn]‐IMP‐1, even though the two metal centers are less than 3.8 Å apart and the iron is high‐spin Fe³⁺, which produces only small PCSs. [FeZn]‐MβLs may be important drug targets, as [FeZn]‐IMP‐1 is enzymatically active and readily produced in the presence of small amounts of Fe³⁺.