Effects of Polyethyleneglycol Chain Length and Phospholipid Acyl Chain Composition on the Interaction of Polyethyleneglycol-phospholipid Conjugates with Phospholipid: Implications in Liposomal Drug Delivery

Purpose. The purpose of this study was to investigate polyethyleneglycol(PEG)-phosphatidylethanolamine(PE) conjugate interaction with phospholipid bilayers, in an attempt to explain the dependence of liposome circulation time on formulation. Methods. Differential scanning calorimetry, electron microscopy, dynamic light scattering and NMR were the major methods used in the study. Results. Mixtures of PEG-phospholipid conjugates and phosphatidylcholine existed in three different physical states: a lamellar phase with components exhibiting some miscibility, a lamellar phase with components phase separated, and mixed micelles. Beyond 7 mol% of PEG(l,000–3,000)-dipalmitoyl phosphatidylethanolamine (DPPE), and 11 mol% PEG(5,000)-DPPE in dipalmitoyl phosphatidylcholine (DPPC), a strong tendency towards mixed micelle formation was observed. All concentrations of PEG(12,000)-DPPE and PEG(5,000)-DPPE beyond 8 mol% formed phase separated lamellae with phosphatidylcholine. Decreasing the acyl chain length from C_16:0 to C_14:0 caused a decrease in tendency towards micelle formation and phase separation. These tendencies increased upon increasing acyl chain length to C_18:0. Phase separation was at least partly due to PEG chain-chain interaction. This was supported by an increased fraction of PEG chains exhibiting a fast NMR transverse relaxation in DPPC/PEG(5,000)-DPPE mixtures as compared to that in distearoyl phosphatidylcholine (DSPC)/PEG(5,000)-dioleoyl-PE (DOPE). Conclusions. These phenomena are discussed in relation to both bilayer and steric stabilization of liposomes, and the lack of prolonged circulation with certain formulations is discussed.     

生物学标志在产肠毒素性大肠埃希菌同源克隆鉴定中的应用

目的研究多方法、多生物学标志在产肠毒素性大肠埃希菌同源克隆鉴定中的作用。方法在毒力基因检测和分型基础上，首次采用质粒分析法结合多位点酶电泳法，对ＥＴＥＣ同源克隆进行了综合研究。结果７个毒力基因型的２０６株散发ＥＴＥＣ菌株经质粒图谱分型后，共可分成９３个质粒型，有１４０株ＥＴＥＣ具有独特的基因型；进一步用多位点酶电泳分型，２０６株ＥＴＥＣ可被分成１４８个ＥＴ型，３种方法综合，共有１９０株ＥＴＥＣ具有独特的基因型。结论多方法、多生物学标志在同源克隆鉴定中能提供更多、更可靠的信息。     

刮治＋自体骨移植术治疗牙源性角化囊肿（附14例报告）

本文总结了１４例应用刮治和自体骨移植术治疗大型牙源性角化囊肿的方法，１４例植骨均成活，４例术后囊肿复发，再次手术，指出：与骨断切除治疗大型角化囊肿的方法比较，此法最大的优点是有利于保持患者面容和咀嚼功能，并对大型角化囊肿的手术原则，自体骨移植问题及手术注意事项进行了讨论。     

Ⅱ孔型房间隔缺损直视修补术后心律失常的临床观察

210例Ⅱ孔型房间隔缺损术后发生心律失常90例,14种类型,共292例次,其中,室上性占96%。30例需药物治疗,93%的患者出院时恢复正常。本文着重分析心律失常的特点,讨论影响因素及预防措施。     

急性病毒性肝炎住院患者血清学分型与流行病学分布研究

本文收集了西安市住院急性病毒性肝炎患者血清标本２９３份，用ＥＬＩＳＡ进行分型检测，并作流行病学调查。结果发现：甲肝占６５．１９％，乙肝占１０．９２％，丙肝占４．７８％，丁肝占３．７５％，戊肝占４．４４％，诊断不明者占１０．９２％。结果表明，在西安市住院的急性病毒性肝炎中，甲肝为主要类型；与以往结果比较，甲肝患者的发病年龄明显后移；除乙肝外，各型肝炎中男性均多于女性，尤以丁肝和戊肝为著；甲肝有明显的     

THE COMPUTERIZED GAIT ANALYSIS SYSTEM AND THREE DIMENSIONAL ANALYSIS OF FOOT-GROUND REACTION FORCES DURING LEVEL WALKING

A S9-2 computerized gait analysis system developed by us is reported. The advantages of the system are: synchronous measurement of the forces, angles and time parameters; high efficiency, accuracy and good repeatability; low cost and easy to operate. A three dimensional analysis of the foot-ground reaction forces of 41 normal subjects during level walking was carried out by the S9-2 system and a series of normal values of parameters and characteristic curves were obtained. The mechanism of formation of the parameters and curves and the sex influence were investigated and discussed. In old subject, before the development of "cautious gait", most values of the parameters did not differ significantly from those of the young subjects, except that the centre of gravity of the body crossing the hip earlier with a slight decrease in the medio-lateral balance capacity.     

The effect of intrauterine devices (stainless steel ring, copper-T220 and levonorgestrel) on the DNA content in isolated human endometrial cells

The effect of three different intrauterine devices on the DNA content in human endometrial cells has been studied in 29 women before and after the insertion of an IUD; a stainless steel ring (9 subjects), Copper-T220 (11 subjects) and a medicated IUD releasing levonorgestrel at a rate of 2 micrograms/day (9 subjects). The material was grouped into "bleeders" (having more than 8 days of bleeding and spotting per month) and "non-bleeders" (having less than 8 days of bleeding and spotting per month). The DNA content was assessed on isolated endometrial cells smeared from thin biopsies and the amount of DNA per cell nucleus was measured by means of a Feulgen microspectrophotometric method. No significant difference was found between the "bleeders" and the "non-bleeders" as to the DNA content. Nevertheless, when the total number of subjects were pooled together, a significant increase in the DNA content was found in the post-insertion specimens in the groups of women using the SS and the T-Cu IUDs. Furthermore, a significant decrease in the DNA content was also found when the specimens obtained after the insertion of the LNG IUD were compared with those obtained after 24 months' use of the stainless steel ring and the Copper-T220 device (p less than 0.01 and p less than 0.002, respectively). It is concluded that the insertion of an inert IUD or an T-Cu IUD, induces significant alterations in the DNA content of the human endometrium adjacent to the device, whereas the use of the LNG device does not significantly modify the DNA synthesis when used for 3-10 months. No correlation was found between the DNA content per cell and the number of days of bleeding and spotting.