Molecular dynamic simulations of the intercalation of benzothiopyranoindazole anticancer analogs with DNA models.

Fixed valence geometry intermolecular energy scans were carried out for a series of eight substituted anti-cancer benzothiopyranoindazoles (BTPI) interacting with (G-C) duplex models for DNA. The apparent intercalation energy minima identified in these scans were subsequently used as starting points in full-cartesian molecular dynamics relaxation simulations for 14 BTPIs. Intercalation in the major groove is preferred when both the ligand and DNA model possess formal charges. Otherwise, insertion of the ligand is modestly preferred from the minor groove. There are multiple minimum energy intercalation complexes within 5 kcal/mol of a global minimum for most analogs studied. The intercalation complex was investigated as a function of the molecular dielectric constant, epsilon, and the length of the (G-C) duplex segment. A wide range of epsilon values (3.5-50) can be employed without changing the relative order of stability of intercalation complexes. However, the absolute intercalation energy is quite sensitive to the selection of epsilon. (G-C)6 duplexes appear to be of adequate length to determine reliable estimates of the relative intercalation energetics.     

诺氟沙星的吸附行为及其测定

诺氟沙星在0.05mol·L^-1NH₄Cl (pH 5.8)溶液中,出现一灵敏的示波极谱还原峰。峰电位为-1.44 V (vs SCE)。峰高与诺氟沙星的浓度在1.0×10^-7～4.0×10^-6mol·L^-1范围内成正比,检出限为5.0×10^-8mol·L^-1,并用于样品的测定。用线性扫描与循环伏安法等手段研究体系的吸附性质。实验表明,该电极过程为具有吸附性的不可逆过程。     

Kalman滤波分光光度法同时测定多相脂质体口服液中氟尿嘧啶和尼泊金的含量

本文提出了对测量值平滑后,用Kalman滤波分光光度法同时测定多相脂质体口服液中氟尿嘧啶和尼泊金的含量,改善了滤波效果,较好地解决了复杂基质存在下多组分的同时测定。用人工合成样考察表明,在269～273nm间滤波结果较好。用分别相当制剂标示量80,100,120%的两组分九种可能组合人工合成样品考查结果表明,氟尿嘧啶和尼泊金的回收率分别为99.3～102.6%和97.8～103.0%;当存在系统误差时,回收率分别为99.4～102.7%和97.0～102.9%     

Intercalation of 7,8-dihydroxy-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene enantiomeric isomers with dinucleoside dimers: a basis for alkylation of the 2-amino group in guanine

The minimum-energy intercalation-complex geometries of the (+/-)enantiomers of 7,8-dihydroxy-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (I) with two dinucleoside dimers were determined. The purpose of these calculations was to see if I could intercalate into DNA in such a way that the observed alkylation of the 2-amino group of guanine could occur subsequent to intercalation. For both dinucleoside dimer sequences, it was found that the (+)-(9 alpha, 10 alpha) isomer could form a stable intercalation complex in which the orientation and distance of the epoxide of I to the 2-amino group of guanine was close to the calculated critical transition-state geometry for the alkylation reaction. The (-)enantiomers can intercalate, but not in a manner close to the transition-state geometry necessary for the alkylation of the 2-amino group of guanine.     

鼠肺门剥脱后肺淋巴引流中断对抗体反应的影响

肺移植后肺感染的发生率比其它器官移植后明显增高，这提示移植肺的免疫反应可能受损。为了研究肺淋巴引流中断对抗体反应的影响，我们用肺门剥脱鼠作为模型，设计了３个实验：（１）用着色淋巴造影术目视检查肺门淋巴管的再生；（２）在支气管内滴注碳粒子后观察粒子从肺到肺引流淋巴结的运输；（３）用羊红细胞使肺免疫后测定抗体反应。结果显示肺门淋巴管被肺门剥脱术所中断，在术后７天开始再生；在术后第１周粒子运输到肺引流淋巴结受阻，此后逐渐恢复正常；在肺门剥脱后７天和１０天免疫的鼠血清抗体反应缺如或低下，其后１月内恢复。由此得出结论，只要抗原不能经淋巴管从肺运送到肺引流淋巴结，肺门剥脱肺内的抗原抗体反应就受到损害。该发现可部分地解释为什么在肺移植后最初几周内经常发生肺感染。     

What did the doctor say--what did the patient hear? Operational knowledge in clinical communication

OBJECTIVES: We aim to introduce Piaget's concept of 'operational knowledge' from the cognitive theory of learning--as a contribution to the broader understanding of clinical interaction. METHOD: Our study involves a theoretical presentation of different kinds and levels of human understanding, illustrated by a case story in which the difference between operational and figurative knowledge was demonstrated. This study used the case story of a male patient aged 80, who was suffering from ulcerative colitis. We appealed to the reader's perceived relevance of these perspectives, in order to understand what was going on between doctor and patient. RESULTS: The case story demonstrates the phenomenon of operational knowledge in the patient, the close links between communicative action and cognitive understanding, and the importance for the doctor of reflecting upon this level of interaction. CONCLUSION: According to the patient-centred clinical method, the doctor should explore the social and emotional context of the patient in order to understand the meaning of the illness. We suggest that a cognitive dimension should also be added, and that the concept of 'operational knowledge' might be useful for such investigations.