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     

雌激素对老年早期大鼠脑心脏毛细血管结构的影响

目的　探讨老年前期大鼠应用雌激素后脑、心微血管结构的变化 ,了解雌激素对脑、心血管的影响 ,为临床合理应用雌激素替代治疗提供实验依据。方法　制作老年早期衰老大鼠模型 ,通过内源性碱性磷酸酶显示法、动脉插管墨汁灌注观察应用雌激素后大鼠脑额叶、海马、下丘脑 ,心脏毛细血管结构的变化。结果　苯甲酸雌二醇组 (estradiolben zoate ,EB)脑额叶皮层、海马、下丘脑、心肌等部位毛细血管面积均明显高于对照组 (P <0 .0 5 )。结论　老年前期雌性大鼠应用雌激素后可影响脑、心脏微血管结构 ,改善心、脑供血     

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.     

当归水溶性多糖的分离、纯化及结构初步分析

采用80℃热水提取，得到当归水溶性多糖W-ASP。经阴离子交换柱层析、凝胶过滤柱层析对其进行纯化分级。实验结果表明：W-ASP11主要由葡萄糖组成，相对分子质量约为380000；W-ASP12主要由半乳糖和阿拉伯糖组成，相对分子质量约为19000；W-ASP2和W-ASP3主要舍半乳糖、阿拉伯糖和鼠李糖以及少量葡萄糖和甘露糖，并含有较高的糖醛酸，由单糖组成及红外图谱初步分析，可判断是一种果胶类多糖。当归多糖主要组分W-ASP3经凝胶色谱（GPC）鉴定为均一组分，其相对分子质量约为62000。     

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.     

Structure and conformation of linear peptides XII. Structure of tryptophanyl-glycyl-glycine dihydrate

The crystal structure of a tripeptide, tryptophanyl-glycyl-glycine dihydrate (C₁₅H₁₈N₄O₄·2H₂O, molecular weight = 354) has been determined. The crystals are orthorhombic, space group P2₁2₁2₁ with a= 7.875 (1) A,b= 9.009(1), c= 24.307(1) and Z = 4. The final R-index is 0.058 for 1488 reflections ((sin θ/λ≤ 0.6 A^?1) with I < 2σ(I). The molecule exists as a zwitterion, with terminal NH⁺₃ and COO^? groups. The peptide units are trans and nearly perpendicular to the plane of the carboxyl group. The backbone torsion angles are: ψ₁= 132.7°, ω₁= 174.2°, φ₂ 88.2°, ψ= 8.6°, ω₂ - 179.8°, φ= - 85.2°, ψ₃₁, = - 178.1°, ψ₃₂ 5.0°. For the sidechain of tryptophan, χ₁= - 171.6°, χ₂ 101.0°.     

Structure and conformation of peptides involving prolyl residue III. L-Prolyl-L-isoleucine monohydrate

The dipeptide, L-prolyl-L-isoleucine monohydrate (C₁₁ H₂₀N₂O₃· H₂O, molecular weight 246.3) crystallizes in the monoclinic space group P2₁, with a = 6.601(3)Å, b = 5.413(3) Å, c = 19.128(6) Å, β= 98.1(1)°, Z = 2, Do = 1.20g·cm^-3 and Dc = 1.208g·cm^-3. The structure was solved by MULTAN–80 and refined to a final R-factor of 0.081 for 594 reflections measured on a Enraf Nonius CAD-4 diffractometer. The peptide linkage exists in the trans conformation. The pyrrolidine ring is disordered with two alternate envelope conformations for the C^γ atom. The values of the sidechain torsion angles are: χ₁₁=– 63.6(17)°, χ₁₂= 171.1(16)° and χ₂=– 59.6(21)° for isoleucine (C-terminal). The crystal structure is stabilized by a three-dimensional network of N—H ? O, O—H ? O and C—H ? O hydrogen bonds. The dipeptide exists in the extended Conformation.