应用电泳技术分析飞行员富含三酰甘油脂蛋白亚组分及其代谢特征

目的 分析富含三酰甘油脂蛋白(TRLs)分子组成及其代谢特征.方法应用脂蛋白电泳技术,对30例飞行员空腹和脂肪负荷餐后血浆做脂蛋白分析,以扫描图面积表示各亚组分构成,观察脂蛋白亚组分变化特点.结果 30例飞行员TRLs清除延迟发生率46.67%.TRLs分子脂蛋白亚组分由极低密度脂蛋白(VLDL)、中密度脂蛋白(IDL)、低密度脂蛋白(LDL)、乳糜微粒(CM)和脂蛋白a[LP(a)]组成.TRLs清除延迟典型扫描图特征为LDL左侧区面积增高,呈双峰或多峰.LDL、VLDL区面积增高,伴有高密度脂蛋白(HDL)面积降低.结论 高三酰甘油血症致动脉粥样硬化作用是在代谢水平异常所致的TRLs清除延迟,TRLs清除延迟是核心环节.     

Crystal structure and conformation of polypeptides: L-leucylglycylglycylglycine

Crystals of L-leucylglycylglycylglycine, LGGG (C₁₂H₂₂N₄O₅), grown from an ethanol-water solution, are orthorhombic, space groups P2₁2₁2₁, with unit cell dimensions (at 22 ± 3°) a = 9.337(1), b = 10.995(1), c = 15.235(1)Å, v = 1563.4 ų, Z = 4 with a density of D_obs= 1.29 g-cm^-3 and D_calc= 1.279 g°cm^-3. The crystal structure was solved by the application of direct methods and refined to an R value of 0.029 for 1018 reflections with I ± 2s?. The molecule exists as a zwitterion in the crystal. The trans peptide backbone takes up a folded conformation at the middle glycylglycyl link accompanied by a significant nonplanarity up to Δω of 8° at the middle peptide and is relatively more extended at the two ends. The molecules are linked together intermolecularly in an infinite sequence of head to tail 1–4′ hydrogen bonds, as is typical of charged peptides. It is interesting to note that while glycylglycylglycine takes up an extended β-sheet conformation, addition of Leu to the N-terminal results in a bent conformation.     

Membrane flow within the myelin sheath in IDPN neuropathy

This report describes some aspects of beta,beta'-iminodipropionitrile (IDPN) neuropathy in rats as observed by ultrastructural methods and X-ray diffraction. Light microscopy shows gross swelling of the axons in proximal lumbar spinal roots 8 days after intraperitoneal injection of IDPN. Mean axon cross-sectional area and mean axon perimeter increased to 280% and 160% of their control values, respectively. At the same time, myelin membrane packing was not visibly disturbed. In addition, X-ray diffraction patterns, recorded under physiological conditions, demonstrate that the myelin lipid bilayer thickness and widths of the aqueous spaces between bilayers did not change. Related observations are made on posterior tibial nerve (PNS myelin) and ventral spinal cord (CNS myelin). The various observations together are interpreted in terms of a fluid myelin membrane. It is proposed that the myelin membrane flows during axon swelling even though normal membrane-membrane contacts are maintained within the sheath. Membrane flow and slippage between membranes are explained in terms of a molecular model of the myelin multilayer.     

人皮质骨矿化基质中骨盐框架结构

目的：研究人皮质骨矿化基质中骨盐的框架结构及框架中骨微间隙。方法：应用透射电镜、场发射扫描电镜观察、电脑图像分析及能谱分析，分析无骨病成人长骨、扁骨２００例骨盐分布特征。结果：骨盐框架结构由微柱、微梁、微小梁、弓状梁、致密点、隔板和骨微间隙构成。骨微间隙由洞、内衬和壁组成，洞平均直径为８４．４±７５．６ｎｍ，与骨小管相比有显著差异（Ｐ值＜０．００１），平均密度为１１～１７个／μｍ２，与骨小管之比超过１０：１。骨盐分针形结晶和微颗粒结晶。结论：骨盐框架结构及骨微间隙是骨盐在人皮质骨矿化基质中的存在形式，可能与骨盐吸收、沉着有关。     

Organization of intensive care units in Europe: lessons from the EPIC study

Objective: To study differences related to intensive care unit (ICU) structure and patient demography between the various countries of Western Europe. Design: Application of data collected by the European Prevalence of Infection in Intensive Care (EPIC) study, a one-day prevalence study. Setting: Voluntary participation of all Western European ICUs. A total of 1417 ICUs responded. Patients: All patients, older than 10 years of age, occupying a bed in the participating ICUs over a 24-h period. 10 038 patient case reports were submitted. Results: The study revealed important differences. In particular, there seems to be a north/south divide with fewer ICU beds and more severely ill patients in the south. The United Kingdom seemed more similar to southern European countries than to the north. Conclusion: While there are similarities between European countries, large differences still remain and are important to identify to enable us to work together to create a more uniform system of intensive care, which will in turn give more effective and efficient patient care. Received: 7 February 1997 Accepted 8 July 1997     

橡胶木粉填充LLDPE复合材料的结构和力学性能

用橡胶木粉填充线性低密度聚乙烯(LLDPE)，研究了酸、碱溶液预处理木粉的效果和硅烷偶联荆(KH-570)、MMA接枝的天然橡胶胶乳(MGL-30)两种改性剂对橡胶木粉表面改性的效果，以及未粉粒径和填充量等对木粉／LLDPE复合材料力学性能的影响，并用SEM对复合材料拉伸断面的形态结构进行了分析。结果表明：木粉的拉径、木粉填充量和改性荆用量对复合材料的力学性能有较大的影响，经碱溶液预处理再用改性荆改性后的木粉能有效地改善木粉与LLDPE的界面粘结强度，提高橡胶木粉／LLDPE复合材料的力学性能。     

大叶紫薇叶中降血糖活性成分的筛选

为筛选大叶紫薇叶中具有降血糖活性的成分,采用3T3-L1细胞葡萄糖消耗模型作为检测手段,对大叶紫薇叶提取物采用HP-20树脂吸附、溶剂萃取、制备薄层分离和制备高效液相分离,导向筛选具有降血糖作用的各分离组分.结果发现,大叶紫薇叶中corosolic acid、熊果酸和总三萜具有降血糖活性.     

同位素扫描图象的数据传输：BCM—80—APPLEⅡ

本文介绍了1种由BCM-80单板机到AppleⅡ微机的图象数据传输方法。这种方法以盒式磁带作为传输工具,并采用AppleⅡ的磁带记录格式将由BCM-80所采集的同位素扫描图象数据传送到AppleⅡ微机之中,进行分析处理,然后输出1幅静止的易于识别和诊断的图象。此种方法不需要增加任何硬件,具有简单、可靠、传输速度快等优点。     

Structural variations in the crystal structures of two homologous DL-Leu and Δ-Leu containing peptides+

The similar conformations and interaction modes of Ac-DL-Leu-Nme₂ and Ac-Δ-Leu-NMe₂ molecules in the solid state allow the comparison of their geometrical parameters. The most evident variations are essentially restricted to the α,β-unsaturated side-chain which adopts the Z-disposition. The dimensions of the peptide backbone are much less sensitive to α,β-unsaturation, with a small shortening by 0.04 Å and 0.02 Å of the N-C^α and C^α-C′ bonds, respectively, and an increase by 6° of the N-C^α- C′ bond angle. The ethylenic and amide groups in the Δ-Leu derivative are far from coplanarity, and a significant electronic conjugation of the π-orbital is likely to be rejected.