Direct determination of sialic acids in serum by capillary electrophoresis with UV detection

A novel method for the determination of N-acetylneuraminic acid (NANA) and N-glycolylneuraminic acid (NGNA) has been developed using high-performance capillary electrophoresis with UV detection at 195 nm, without pre or post-column derivatisation. The acids were separated in a 50-cm, fused-silica capillary (50 mu m i.d, 45.5-cm effective length) with Na2B4O7-Na2HPO4 buffer. The detection limit for NANA is a concentration of 9.6 x 10(-6) M or, in terms of mass: 3.879 x 10(-14) mol (39 fmol). This method is applicable to determination of NANA in normal human serum. The results were also compared with those of the colorimetrie method.

Capillary electrophoresis of urinary normal and modified nucleosides of cancer patients

This paper gives a capillary electrophoretic method for the separation of 15 urinary normal and modified nucleosides from cancer patients in less than 40 min. A 500 mmx50 mu m uncoated capillary column (437.5 mm to window) was used. The effects of the voltage and the sodium dodecyl sulfate (SDS) concentration in the buffer on the separation were studied. With reproducibilities of migration times better than 1.2% (R.S.D.) and determined concentrations better than 5-25%, depending on the concentrations of nucleosides in the urine, the analytical characteristics of the method were food. Using this developed method, the concentrations of 13 normal and modified nucleosides, extracted on a phenyl boronic acid affinity chromatography column, in 25 urines from patients of 14 kinds of cancer were determined. The levels (nmol/mol creatinine) of modified nucleosides in urines from cancer patients were increased as compared with those in normal urines. (C) 1998 Elsevier Science B.V.

Synthesis and characteristics of the human serum albumin-triazine chiral stationary phase

Human serum albumin (HSA) was successfully bonded to silica with s-triazine as activator. The coupling reaction by this method was rapid and effective. The triazine-activated silica is relatively stable and can be installed for at least 1 month without obvious loss of reactivity when stored below 30 degreesC, pH below 7. It was observed that the amount of bound HSA reached 120 mg/g silica calculated from the UV absorbance difference of the HSA solution. d,l-tryptophan was selected as the probe solute to characterize the properties of HSA bonded s-triazine chiral stationary phase, and separation factor of 9.4 was obtained for d,l-tryptophan. Furthermore, the amount of effective HSA on silica was measured by high-performance frontal analysis, and only 16.8 mg/g silica was responsible for the resolution of d,l-tryptophan. These results indicate that the amount of both the bound and effective HSA on silica with triazine as activator was much higher than those by the Schiff base coupling method. Different kinds of enantiomers were resolved successfully on the aminopropylsilica-bonded HSA s-triazine chiral stationary phase. (C) 2000 Wiley-Liss, Inc.

环境、单胺类神经递质系统对脑的某些高级认知功能的影响

一些特殊的环境因素如：丰富环境、应激等能够对脑的某些高级认知功能产生广泛的影响。单胺类神经递质系统对脑的高级认知功能也起着重要的作用。我们在前人的工作基础上，通过实验进一步探讨了丰富环境、束缚应激及社会等级与抑郁症、焦虑症的关系，以及去甲肾上腺素β 受体系统与吗啡诱导的条件化环境线索记忆的获得和提取之间的关系。我们首先假设在未成年小鼠每天接受束缚应激刺激之后饲养于丰富环境中可能也会减轻小鼠慢性束缚应激导致的焦虑样或抑郁样的行为。经过14 天和28 天两个周期的环境处理，结合每天4 小时和8 小时的束缚应激和每天16 小时的丰富环境饲养，利用动物行为学方法检测小鼠焦虑样或抑郁样的行为。实验结果表明：（1）慢性束缚应激抑制了未成年小鼠体重的增加，丰富环境可能也是抑制体重增加的因素之一；（2）在强迫游泳测试中，慢性束缚应激可减轻未成年小鼠抑郁样的行为，但是丰富环境能够抑制束缚应激引起的未成年小鼠抑郁样的行为的降低，即丰富环境加重了其抑郁样的行为；（3）在黑白箱测试中，丰富环境能够提高未成年小鼠自发探索活动能力，但是对束缚应激引起焦虑样行为的降低没有影响。我们的第二个实验假设高等非人灵长类动物猕猴（Macaca mulatta）天然的社会等级关系产生的抑郁样的个体能够更好的模拟人类社群中自然形成的抑郁症的发病与病征，因此可能成为研究人群中自然状态下产生的抑郁症潜在的更为有效的实验动物模型。我们对几个猕猴群体的不同结构组成（性别、年龄、数量等）进行观察分析，首先筛选出抑郁样的猕猴个体，进而探讨在不同结构组成的猕猴群体中产生抑郁样个体的情况。结果表明：（1）社会等级地位高低与猕猴抑郁发病密切相关即最低地位的个体产生抑郁样个体的可能性最大；（2）猕猴群体密度增加，产生抑郁样个体的几率有增高的趋势；（3）在猕猴群体中产生雌性抑郁样个体几率有高于雄性的趋势；（4）抑郁样个体的产生可能与猕猴的年龄、群体性别构成等因素相关性不高。根据以往的研究发现阻断肾上腺素β受体干预环境条件化线索相关记忆的再巩固能够加快成瘾记忆的消退，却很少涉及β受体对这种记忆的获得和提取的影响。因此，我们利用小鼠吗啡诱导的条件化位置偏好模型和药理学方法探讨了β受体拮抗剂心得安对吗啡相关的环境条件化记忆的获得和提取的影响。实验结果表明：β受体不参与吗啡诱导环境线索记忆的获得，但可能加强记忆的提取，提示激活β受体可能加快对吗啡依赖条件化环境线索相关记忆的消退。

Pyrazine-containing Acene-Type Molecular Ribbons with up to 16 Rectilinearly Arranged Fused Aromatic Rings

A series of acene-type conjugated molecules(1-5) containing 2-6 pyrazine units and up to 16 rectilinearly arranged fused aromatic rings were synthesized by condensation coupling of 1,2-diamines and 1,2-diketones. The energy gap of the molecules estimated from absorption edge decreases with an increase in molecular length, indicating the well-delocalized nature of the molecules. The cyclic voltarnmetry measurements suggest that the n-type properties of these ribbonlike pyrazine derivatives are dependent on the molecular length and the number of the pyrazine units.

16-O-去甲基乌头碱的生物转化及电喷雾质谱研究

采用乌头碱和人肠内细菌体外温孵的方法,探讨乌头碱在肠内的生物转化规律.乌头类生物碱在ESI正离子模式条件下形成质子化分子[M+H]+,利用离子阱电喷雾串联质谱和傅立叶离子回旋共振电喷雾串联质谱方法可以直接分析乌头碱的转化产物.本文首次报道了乌头碱在人肠内菌群环境中产生16-O-去甲基乌头碱,16-O-去甲基乌头碱可进一步被肠内细菌转化,通过脱乙酰基、脱苯甲酰基、脱甲基、脱羟基以及酯化反应,产生新型的单酯型、双酯型和20余种脂类生物碱等转化产物.