Evidence for regular distribution of sterols in liquid crystalline phosphatidylcholine bilayers.

To investigate the lateral organization of sterols in membranes, the fluorescence intensity of dehydroergosterol at different mole fractions in liquid crystalline dimyristoyl phosphatidylcholine bilayers was examined. A number of intensity drops were observed at specific mole fractions, as predicted from a hexagonal super-lattice model. The fluorescence dips provide compelling evidence that a naturally occurring sterol is regularly distributed at fixed compositional fractions, consistent with the presence of hexagonal super-lattices in the fluid membranes. Regularly distributed regions, however, coexist with irregularly distributed regions. The extent of regular distribution varies periodically with sterol mole fraction and, consequently, similar variations take place in the membrane volume and lipid packing. This level of modulation in local membrane structure by minute changes in sterol concentration should have profound implications for the functional role of cholesterol content in cell membranes.     

Sequence analysis of the gene encoding the Chlamydia pneumoniae DnaK protein homolog.

The antigen-coding region of a 4.2-kb PstI fragment of Chlamydia pneumoniae (pLC3), which encodes a 75-kDa immunoreactive protein recognized during human C. pneumoniae infection, was localized to a 2.0-kb EcoRI fragment. This subclone expressed an immunoreactive fusion protein of ca. 82 kDa. Nucleotide sequence analysis of the C. pneumoniae gene revealed that it consisted of a 1,980-base open reading frame with an inferred 71,550-Da protein of 660 amino acids. Putative Escherichia coli-like promoters and a ribosomal binding site were located in the 5' upstream region, and an 11-base dyad forming a stable stem-loop structure following two in-frame stop codons was identified. The C. pneumoniae 75-kDa protein is a member of the hsp70 family of heat shock proteins and has 87% amino acid similarity with the Chlamydia trachomatis protein.     

Antiviral triterpenes fromPrunella vulgaris

Two triterpenes 1 and 2 with antiviral activity againstHerpes simplex virus type 1in vitro were isolated fromPrunella vulgaris. Each compound caused a significant reduction in viral cytopathic effect whenvero cells were exposed to them for 72 hours after viral challenge. They were identified asbetulinic acid(1) and 2α, 3α-dihydroxyurs-12-en-28-oic acid(2) on the basis of their spectroscopic properties. The antiviral activity of them was estimated as EC₅₀=30 μg/ml(1) and 8 μg/ml(2), respectively by plaque reduction assay.     

T cell immunodeficiency in dyskeratosis congenita.

Dyskeratosis congenita has been found to be associated with abnormal immune function. In this study we report a patient with this association. He developed Pneumocystis carinii interstitial pneumonia, and impaired cell mediated immunity was confirmed by the presence of depressed lymphoproliferative responses to in vitro stimulation with mitogen. Enumeration of T cell subsets showed a severely depressed CD4:CD8 ratio (0.38), which is the likely cause for impaired cell mediated immunity. The T cell activation pathway appeared intact, as his T lymphocytes were able to express activation markers (CD25 and HLA-DR) after mitogen stimulation.     

浅谈血液层流病房净化工程招标技术管理

1招标内容:血液层流病房净化工程,包括: 1.1血液层流病房净化工程范围: 1.2血液层流病房净化工程方案设计; 1.3血液层流病房净化工程设备、材料的供应与安装; 1.4血液层流病房净化工程施工组织; 1.5病房及辅助功能区内的配套设施的施工与安装.     

保留肋间臂神经乳腺癌腋窝清扫术85例

目的：探讨乳腺癌腋窝清扫术保留肋间臂神经的临床意义。方法：在85例乳腺癌腋窝清扫术中，采用腋静脉下方途径保留肋间臂神经，术后观察其效果。结果：84例保留肋间臂神经成功，1例不慎切断。术后上臂内侧感觉异常发生率为4．7％(4／85)，2周后症状消失。随访均未发现局部复发。结论：乳腺癌腋窝清扫术中保留肋间臂神经，可明显减少上臂内侧感觉障碍的发生率，有利于提高患术后生活质量。     

深圳市SARS流行病学调查分析

目的 描述深圳市SARS的流行病学特点，为进一步制定预防控制对策提供信息支持。方法 通过对医院收治的53例病人进行病例汇总及流行病学调查，描述流行概况。结果 深圳市53例SARS患者男比女为1．4：l，20～40岁的有29人(54．7％)。2、3月为发病高峰期；发病地点罗湖区及福田区各为19、20例；发病职业分布无差异。53例中30人(56．6％)有接触史或／及去广东其他城市、香港旅游史，其中于医院接触而发病的有9例(17．0％)。53例中有5个家庭发生家庭聚集病例，2个单位出现群发病例，共累及21人(39．6％)．死亡2人。深圳医护人员无一人发病。结论 此次SARS于深圳流行过程中，以青壮年发病多见，男性发病稍多．发病地点多为人口密集的商业区，多有接触史或／及旅游史，呈家庭聚集及单位群发的特点。严格实行消毒隔离措施，并坚持服用病毒唑等抗病毒药物可有效防止SARS在医院内的传播。     

日本血吸虫亲免素基因的扩增及序列分析

[目的]研究日本血吸虫亲免素基因编码序列的结构及进行初步的功能预测.[方法]用5'端和3'端锚定PCR从尾蚴文库中扩增,以获取日本血吸虫中国大陆株亲免素基因完整的开放阅读框(open readingframe,ORF);用生物信息学技术确认其是否为亲免素编码基因并进行结构功能的初步分析和预测.[结果]用5'端和3'端锚定PCR从尾蚴文库中获得了亲免素基因5'端和3'端所缺序列,得到的亲免素基因cDNA的总序列长为1 438 bp,其ORF长1 296 bp,编码431个氨基酸.利用生物信息学技术鉴定其为日本血吸虫亲免素基因的完整cDNA序列.并用RT-PCR从日本血吸虫尾蚴mRNA扩增出亲免素基因的ORF.[结论]成功获得了日本血吸虫亲免素编码基因的全长cDNA,为进一步的功能研究打下了基础.     

Influence of finishing time on marginal sealing ability of new generation composite bonding systems

Although variation in finishing techniques has been shown to affect microleakage, little research has been published on the influence of finishing time on the marginal sealing ability of new generation composite bonding systems. The objective of the present study was to evaluate the influence of finishing time on the enamel and dentine marginal sealing ability of four new generation composite systems. Two class V preparations, which were solely in enamel or dentine, were made on the buccal surfaces of 96 freshly extracted molar teeth. The teeth were randomly divided into four groups of 24 and restored with composite resin (Silux Plus^®) utilizing the following bonding systems: Scotchbond Multi-purpose^®, Fuji Bond LC^®, Prime & Bond 2·0^® and Bisco One-step^®. Half of the restorations in each group were finished immediately after light polymerization and stored for 1 week. For the remaining restorations, finishing was delayed for 1 week. The storage medium was isotonic saline at 37°C throughout the experiment. All restorations were then thermocycled, subjected to dye penetration testing, sectioned and scored. The results suggest that the finishing of composite restorations, bonded with the bonding systems evaluated, should be carried out immediately after light polymerization. Delayed finishing does not improve but instead can be detrimental to the marginal seal of the restorations. The effects of delayed finishing are, however, both bonding system and tissue specific.