紫外分光光度法测定发酵液中胞二磷胆碱钠含量

基于紫外分光光度法,建立了一种胞二磷胆碱钠发酵液分离纯化过程中胞二磷胆碱的分析方法。研究表明,在265 nm的波长下胞二磷胆碱吸光度不受溶液pH影响,并且在10~30℃的范围内基本保持稳定;发酵液稀释到一定浓度后分析,可使蛋白质对其吸光度影响1.5%。在5~100μg/mL的范围内线性关系良好(R2=0.999 7),平均加标回收率为100.87%,相对标准偏差(RSD)为0.178%,准确度较高及重现性好。     

The labeling of brain ethanolamine phosphoglycerides from cytidine diphosphate ethanolamine in vitro

Chicken brain microsomes convert¹⁴C-ethanolamine-labeled cytidine diphosphate ethanolamine (CDPE) to ethanolamine lipids (EPG) at a measurable rate. Mitochondria and particle-free supernatant fractions are almost inactive. On adding saturating amounts of diacyl glycerol to the microsomes, formation of EPG increases 10-fold, and is almost totally confined to the diacylsn-glycero-3-phosphorylethanolamine (GPE), whose synthesis increases 20-fold (from 13.1 to 249 mμmoles/mg protein/hr). The addition of the 1-alkenyl 2-acyl glycerol also produces a noticeable increase in the rate of EPG labeling, which is almost exclusively confined to the alkenyl acyl GPE, whose synthesis is stimulated 30-fold (from 3.1 to 90 mμmoles/mg protein/hr). Synthesis of alkyl acyl GPE from CDPE was not detected in the brain microsomes. Synthesis of EPG from CDPE by chicken brain homogenates has also been examined and results similar to those reported for the brain microsomes were obtained. In addition, small amounts of labeled alkyl acyl GPE are produced from CDPE in the homogenates, but in no case does this synthesis increase on adding various lipid acceptors to the incubation system. Various properties of the phosphorylethanolaminediacyl glycerol phosphotransferase (E.C. 2.7.8.1) of brain microsomes were examined. It is concluded that the enzymic activities which convert CDPE to diacyl GPE and alkenyl acyl GPE, respectively, are similar.     

毛细管气相色谱法同时测定三磷酸胞苷二钠中5种有机溶剂残留量

研究建立了同时测定三磷酸胞苷二钠中乙醇、丙酮、氯甲醚、甲苯、苯乙烯5种有机溶剂残留量的毛细管气相色谱法。样品以乙腈为溶剂,经DB-FFAP(30 m×0.32 mm×0.25μm)毛细管柱分离,氢火焰离子化检测器检测,这5种有机溶剂呈良好的线性响应,平均回收率在98.3%~99.5%,精密度RSD在0.21%~1.92%,最低检出限可达5.0~7.5 mg/kg。本方法简单、灵敏、准确,完全能满足药品中所述有机溶剂残留量的测定要求。     

Inhibition by adenosine triphosphate of heart microsomal neutral lipase activity

Triacylglycerol lipolysis was inhibited by palmitate, in the isolated perfused normal rat heart. Acetate or acetylcarnitine could reproduce the inhibitory effects of palmitate. Since heart neutral lipase plays an important role in the lipolysis of heart triacylglycerols, the effects of acetylcarnitine, acetyl CoA and related metabolites on the microsomal neutral lipase activity were studied. ATP inhibited the enzyme activity in a concentration-dependent manner without a lag phase. AMP and adenylyl imidodiphosphate, two compounds structurally related to ATP but whose phosphate groups cannot be transferred, did not inhibit the microsomal lipase activity. These results suggested that ATP inhibited the lipase activity through the transfer of its phosphate group. It is proposed that cellular ATP concentration is a determinant of tricylglycerol lipolysis in the heart.     

三磷酸胞苷二钠注射液细菌内毒素检查法的研究

考察三磷酸胞苷二钠注射液细菌内毒素检查方法。按《中国药典》2000年版二部,制定本品细菌内毒素限值,并研究三磷酸胞苷二钠注射液对细菌内毒素检查试验的干扰情况,以确定本品是否适用细菌内毒素检查法。本品可采用细菌内毒素检查法,并建立了本品细菌内毒素检查法质量标准。     

Role of indium in promoting anodic dissolution of Al-In alloys in non-aqueous electrolyte

Exploratory work on the anodic dissolution behaviour of aluminium and aluminium binary alloys in electrolytes in non-aqueous organic solvents is reported. Commonly used electrolytes for non-aqueous battery systems were selected on the basis of their conductivities and activities for anodic dissolution of Al and Al-alloy anodes. It is found that Al–In alloy electrodes exhibit an exceptionally active anodic dissolution behaviour in a 1 M solution of AlCl₃ in anhydrous acetonitrile. The steady-state Tafel polarization plots for dissolution of pure Al, Al–Sn, Al–Ga and Al–In alloy anodes are compared, and a.c. impedance spectra for an Al–In alloy anode in 1 M solution of AlCl₃ in CH₃CN are evaluated and discussed. The In component, like Ga or Hg, interferes with passivation of Al during its anodic dissolution and thus promotes an active condition on the metal surface leading to relatively high anodic dissolution current-densities at substantially negative electrode potentials.     

尿苷二磷酸与尿苷三磷酸两种佐剂对HAV抗原及HBsAg诱导小鼠体液免疫应答的影响

目的探讨尿苷二磷酸(Uridine diphosphate,UDP)与尿苷三磷酸(Uridine triphosphate,UTP)两种佐剂对HAV抗原和HBsAg诱导小鼠体液免疫应答的影响。方法分别在HBsAg(1μg)和HAV抗原(18 EU)中加入不同浓度的UDP和UTP(HBsAg组:UDP和UTP均500μg及1、2、5、10 mg,HAV抗原组:UDP和UTP均500μg及1、2 mg),均经腹部皮下多点注射免疫ICR小鼠(HBsAg组:2针,间隔2周,0.1 ml/只;HAV抗原组:单针免疫,0.2 ml/只),并设空白对照组(生理盐水100μl)、抗原组对照组(HBsAg 1μg;HAV抗原18 EU)、铝佐剂组对照组(铝佐剂300μg)、UDP+铝佐剂复合组(HBsAg 1μg+铝佐剂300μg+UDP 2 mg;HAV 18 EU+铝佐剂300μg+UDP 2 mg)和UTP+铝佐剂复合组(HBsAg 1μg+铝佐剂300μg+UTP 2 mg;HAV 18 EU+铝佐剂300μg+UTP 2 mg),分别于末次免疫后(HBsAg组:第4、8、12和16周;HAV抗原组:第4、8、12周)采血,分离血清,ELISA法检测小鼠血清中抗-HBsAg IgG和抗-HAV IgG水平。免疫18周后,分别取HBsAg组中UDP和UTP最佳浓度组及空白对照组小鼠心脏、肝脏、脾脏、肾脏及肺组织进行病理观察。结果除空白对照组小鼠血清检测不到抗-HBsAg IgG外,其余各组小鼠血清抗-HBsAg IgG及抗-HAV IgG水平均在第8周达到峰值,以后逐渐下降。末次免疫后,UDP及UTP各组抗-HBsAg IgG及抗-HAV IgG水平均高于抗原对照组,差异均有统计学意义(P均<0.05)。HBsAg组UDP+铝佐剂复合组产生的IgG水平明显高于抗原对照组、铝佐剂对照组及UDP和UTP各浓度组(P<0.05);HAV抗原组UTP+铝佐剂复合组产生的IgG水平明显高于抗原对照组、铝佐剂对照组及UDP和UTP各浓度组(P<0.05)。在两种抗原中,UDP和UTP的最佳浓度均为2 mg/只。在设置的浓度范围内,UDP和UTP佐剂均未观察到毒性反应。结论UDP和UTP均能明显增强HBsAg及HAV抗原诱导小鼠的体液免疫应答。     

加入WTO与我国玻璃纤维工业

加入WTO是我国改革开放进程中的一次巨大飞跃,对我国经济、社会、意识观念以及各个行业的发展将会产生久远、深刻的影响. 作为一种处于旺盛发展时期的新型材料,我国玻璃纤维工业如何顺应经济全球化的历史潮流,力争在广泛的国际经济合作和激烈竞争中发展自己、保护自己,实现跨越式的飞跃,这是整个行业极为关注的大事.在本文中我们试图就玻纤行业迈入WTO门槛前后存在机遇和面临困难进行几点探讨.     

Radical entry into particles during emulsion polymerization of vinyl acetate

The entry of free radicals (formed in the aqueous phase) into polymer particles is the subject of the present work. A model has recently been developed based on the postulate that the aqueous-phase growth of the free radicals to a critical size is the rate-determining step for entry. An experimental strategy was devised to study this phenomena. Polystyrene latex with a water-insoluble inhibitor partitioned into the polymer particles was used as seed for secondary polymerization of vinyl acetate. This was done to form and isolate stable oligomers of the critical size. The presence of vinyl acetate oligomers was detected with Fourier transform infrared spectroscopy and thin-layer chromatography. Fast atom bombardment–mass spectroscopy (MS) was used to determine the molecular weights of the oligomers. Though it was not possible to determine the precise size of the vinyl acetate oligomers formed, the MS results show that the number of monomer units in the oligomers has an upper bound of 12–14. The number of units in the oligomer of critical size was estimated to be about 5–6. These experimental results are quite close to model predictions; thus this work helps in corroborating the model. Additional work is necessary to conclusively validate this model. The experimental strategy used in this work has made it possible to determine the approximate size of oligomers formed in the aqueous phase during emulsion polymerization. © 1994 John Wiley & Sons, Inc.     

Hydrogen entry into Fe and high strength steels under simulated atmospheric corrosion

Electrochemical hydrogen permeation tests of Fe sheets under two cyclic corrosion test (CCT) conditions were performed to understand hydrogen entry behavior under atmospheric corrosions. Hydrogen entry into 1300 MPa-class high strength steels under two CCT conditions was also investigated using thermal desorption analysis. One CCT consisted of salt spray, dry and wet stages (Salt Spray CCT; SSCCT), and the other consisted of dry and wet stages after NaCl deposition (Dry–Wet CCT; DWCCT). The corrosion rates of Fe and the steels were almost constant under SSCCT and they decreased under DWCCT with time. Nevertheless, both CCTs resulted in increases in hydrogen permeation current and diffusible hydrogen content with time indicating enhancement of hydrogen entry. Corrosion current monitored by means of an atmospheric corrosion monitoring sensor consisting of Fe anode and Ag cathode decreased obviously under dry stage of the CCTs, whereas hydrogen permeation was high at the beginning of the dry stage. The discrepancy between hydrogen entry and corrosion rate indicates that the hydrogen entry is not directly controlled by corrosion rate. Increase in acidity of underlying rust layer with growth of rust layer monitored using a W/WO₃ electrode is considered to be one of the factors affecting the hydrogen entry efficiency.     

Incorporation into lipid classes of products from microsomal desaturation of isomerictrans-octadecenoic acids

The microsomal desaturation of positional isomers oftrans-octadecenoic acids is effected by the Δ9-desaturase and, with concomitant geometric isomerization,cis,trans- andcis,cis-octadecadienoic acids of unusual structure are formed. Incorporation of the substrates and their products into lipids varied from 50.5% for incubations with 14–18∶1 to 81.0% for 6–18∶1. A detailed study of the composition of each of the major lipid classes, i.e., phospholipids, triacylglycerol and cholesteryl esters, as well as the composition of the free fatty acid fraction, revealed a complex picture. Generally, thec,c-18∶2 products were enriched in the phospholipid fraction, whereas thec,t-18∶2 appeared preferentially in cholesteryl esters. The 18∶1 substrates themselves did not show marked preferences for any of the lipid classes. Phospholipase A₂ action on phosphatidylcholine and phosphatidylethanolamine demonstrated enrichment of thec,c- and thec,t-18∶2 products in the 2-position, whereas the 18∶1 substrates were preferentially inserted into the 1-positions. Thec,c- andc,t-18∶2 formed by desaturation oft11–18∶1 varied from this pattern, probably due to their conjugated double bond structures. Linoleic acid,c9,c12–18∶2, formed during desaturation oft12–18∶1, surprisingly showed enrichment in the 1-position of phosphatidylcholine. Incubation experiments witht5- andt6-isomers using liver microsomes from rats fed a corn-oil-supplemented diet showed conversion and incorporation rates similar to the rates obtained with microsomes from EFA-deficient rats. The fatty acid composition of lipid classes and the distributions of products and substrate between the 1- and 2-positions of phosphatidylcholine also agreed with results obtained using microsomes from EFA-deficient rats.     

Sterol pathway in yeast. Identification and properties of mutant strains defective in mevalonate diphosphate decarboxylase and farnesyl diphosphate synthetase

Yeast mutant strains auxotrophic for ergosterol and blocked in mevalonate diphosphate decarboxylase (erg19) and farnesyl diphosphate (FPP) synthetase (erg20) were isolated. The main feature of the mutants blocked in FPP synthetase is their ability to excrete prenyl alcohols, such as geraniol and farnesol. The isolation of the functionalERG20 gene allowed us to show that farnesyl diphosphate synthetase could be a rate limiting enzyme in ergosterol biosynthesis in yeast. Based on a paper presented at the symposium on Plant and Fungal Sterols: Biosynthesis, Metabolism and Function, held at the AOCS Annual Meeting, Baltimore, MD, April 1990.     

Promotion of hydrogen entry into iron from NaOH solution by iron-oxygen species

This study was carried out to explain reasons of the enhanced hydrogen entry into iron at low polarisations. Hydrogen permeation rate (HPR) through a 35-μm thick iron membrane was studied with the electrochemical technique in 0.1 M NaOH at 25 °C. A rotating split-ring disk electrode was used to detect soluble Fe(II) species. Enhanced hydrogen entry (HPR peaks) was observed at low cathodic and low anodic polarisations during voltammetric cycling, and also during galvanostatic anodic polarisation applied after cathodic charging. HPR peaks occurred at potentials from about −1.2 to −0.9 V (NHE) which were more cathodic than the potentials of thermodynamic stability of Fe(OH)₂ or Fe₃O₄, and of the formation of soluble Fe(II) species. It has been suggested that the enhanced hydrogen entry is associated with the presence of FeOH_ad. In this species oxygen is bound with hydrogen (oxo-hydride), hence it can be supposed that the mechanism of its promoting effect can be similar to that of hydrides of other elements of the VIb group.     

Functional properties of subunit interactions in human cytidine deaminase

An intersubunit interactions study related to the active sitehas been performed on the wild-type cytidine deaminase (CDA)and on the mutant enzyme F137W/W113F. F137 is the homologousto the Bacillus subtilis CDA F125 involved in the subunit interactions.In the presence of SDS, wild-type human CDA dissociates intoenzymatically inactive monomers without intermediate forms viaa non-cooperative transition. Extensive dialysis or dilutionof the inactivated monomers restores completely the activity.Circular dichroism measurements show that the secondary/tertiarystructure organization of each subunit is unaffected by theSDS concentration, while the mutation Phe/Trp causes weakeningin quaternary structure. The presence of the strong human CDAcompetitive inhibitor 5-fluorozebularine disfavours dissociationof the tetramer into subunits in the wild-type CDA, but notin mutant enzyme F137W/W113F. The absence of tyrosine fluorescenceand the much higher quantum yield of the double mutant proteinspectrum suggest the occurrence of an energy transfer effectbetween the protein subunits. This assumption is confirmed bythe crystallographic studies on B.subtilis in which it is shownthat three different subunits concur with the formation of eachof the four active sites and that F125, homologous to the humanCDA F137, is located at the interface between two differentsubunits contributing to the formation of active site. Received February 10, 2003; revised October 14, 2003;; accepted October 21, 2003