Impact of elective single embryo transfer on the twin pregnancy rate

BACKGROUND: It is unclear how the implementation of elective single embryo transfer in clinical practice would affect clinical pregnancy and delivery rates and multiple birth rates. METHODS: This retrospective study analysed 1871 IVF/ICSI cycles carried out from 1997 to 2001 in the IVF programme of a single university infertility clinic. RESULTS: The number of elective single embryo transfers increased from 11 to 56%. At the same time the clinical pregnancy rate was relatively stable; mean 34.0% (range 28-42). The number of embryos per embryo transfer decreased from 1.8 to 1.3. The multiple pregnancy and delivery rates dropped markedly from 25 to 7.5% and from 25 to 5% respectively. CONCLUSIONS: An elective single embryo transfer programme can be adopted in daily practice that decreases the twinning rate to <10% and does not affect the overall pregnancy rate.     

前列地尔Lipo-PGE1干预肝脏血流灌注的实验研究

目的： 探讨前列地尔脂微球(liposome prostaglandin E₁,Lipo-PGE₁) 不同用药时间和途径对肝脏血流灌注的作用机制。方法: 选取健康成年犬12只，经左小隐静脉注射Lipo-PGE₁₁ μg/kg，速度均为0.05 μg·kg^-1·min^-1。分别于0 min、5 min、15 min、30 min后行肝脏CT灌注成像（computed tomography perfusion imaging，CTPI）扫描，计算肝动脉灌注量(hepatic arterial perfusion,HAP)、门静脉灌注量 (portal vein perfusion,PVP)、总肝灌注量（total liver perfusion,TLP），对照分析不同时间Lipo-PGE1对肝脏血流灌注的影响。选取健康成年犬24只，随机平均分成4组：对照组、外周静脉用药组、肝动脉组、肠系膜上动脉组。Lipo-PGE₁的用药量均为1 μg/kg、用药速度均为0.05 μg·kg^-1·min^-1，0.9%生理盐水用量为20 mL。各组用药5 min后行肝脏CTPI，比较分析不同途径给予Lipo-PGE₁对肝脏血流灌注的影响。结果: 经外周静脉注射Lipo-PGE10 min、5 min、15 min、30 min后CTPI测量的HAP(mL·min^-1·mL^-1)分别为：0.22 ±0.65、0.24±0.65、0.22±0.69、0.22±0.06；PVP (mL·min^-1·mL^-1)：1.22±0.40、1.88±0.59、1.55±0.55、1.29 ±0.57；TLP (mL·min^-1·mL^-1)分别为：1.44±0.42、2.12±0.61、1.77±0.56、1.51±0.58。方差分析显示HAP组间比较无显著差异（F=0.249，P>0.05），而PVP、TLP组间比较有显著差异（F=3.812，P<0.05）、（F=3.805，P<0.05）。5 min组PVP、TLP增加最为显著，15 min、30 min时两者仍处于高值水平。对照组和外周静脉组、肝动脉组、肠系膜上动脉组的HAP (mL·min^-1·mL^-1)分别为：0.22±0.06、0.24±0.06、0.31±0.07、0.26±0.05；PVP (mL·min^-1·mL^-1)分别为1.28±0.38、2.33±0.41、2.37±0.55、2.83±0.94；TLP (mL·min^-1·mL^-1)分别为：1.50±0.40、2.57±0.42、2.67±0.58、3.09±0.94。方差分析显示HAP组间比较无显著差异（F=2.248，P>0.05），而PVP、TLP组间比较有显著差异（F=6.892，P<0.01）、（F=7.802，P<0.01）。经肠系膜上动脉给药较其它途径给药PVP、TLP增加趋势更为显著。结论: Lipo-PGE₁能显著增强肝脏血流灌注，且主要影响门静脉灌注分量，介入技术可为快速改善肝血流灌注提供有效途径。     

Web-based Diagnostic Imaging Service Using XML Forms

Traditionally, radiology has been conceived as a support department providing patient scanning services to the other clinical departments in a hospital. However, recent advancements in networking technology and related information systems such as picture archiving and communication system (PACS) and radiology information system (RIS) provide new opportunities for inventing different types of diagnostic imaging businesses such as teleradiology. In this article, we examined the business processes of currently operating imaging centers and proposed a prototype of an information system that can facilitate their workflows in a more efficient way. The principal component of our proposed system is a report management module built on extensible markup language (XML) technologies that allows much flexibility and convenience for both imaging technicians and radiologists.     

Assessing the conditions forin vivo electrical virtual biopsies in Barrett's oesophagus

It has previously been shown that it is possible to differentiate between squamous and columnar epithelia in rat and resected human tissues using an impedance probe to makein vitro measurements. This probe can be passed down an endoscope allowing measurements to be made in patients. However, the probe emerges parallel to the oesophageal wall, with little room to manoeuvre. The conditions of control required to give reliable readings have been investigated. The importance of pressure applied and the angle of approach to the oesophagus was assessed. Pressures in the range 26.6 Pa to 46.3 kPa and angles in the range 15–90 degrees were considered. Inin vitro studies it was observed that it was possible to obtain consistent readings with pressures greater than 2.9 kPa and with angles greater than 15 degrees between the probe and the oesophagus. These conditions can be achievedin vivo, and readings obtained from twelve patients are shown (45 readings on normal squamous, 34 on Barrett's oesophagus and 22 on stomach). At low frequencies (9.6–153.2 kHz), a Mann-Whitney test shows a significant difference (p<0.001) when comparing the means from squamous and columnar, and also when readings from Barrett's and normal gastric epithelia are compared (p<0.001).     

Some notes on uncertainty; Federal policy and innovation

The legislative background and current responsibilities of the new National Center for Health Care Technology (NCHCT) are discussed. The NCHCT's charge is to consider the stage of development, the actual or potential risks, costs and rate of use of health care technology. The role of Government in supporting new technologies, stimulating innovation and encouraging application of research products is considered. These issues are discussed in the context of the uncertainty inherent in planning and the formulation of public policy.     

人体组织中血液灌注率和动脉血温度的无损测量研究

由于人体组织中存在血液对流传热和代谢产热，当皮肤表面绝热后，皮肤表面的温度将上升，体表温升值是人体组织中血液灌注率和动脉血温度的函数，根据实际测量的体表温升与时间的关系就可以测出活体组织的血液灌注率和动脉血温度。根据一维Pennes生物传热方程，推导出了体表绝热后人体组织中及皮肤表面温度分布的解析解，并对人体组织中的血液灌注率及动脉血温度进行了实验测量。由于测量过程中利用的只是皮肤表面的温度信息，无须引入外加热源，对人体组织完全不会造成损伤，亦避免了干扰人体组织的正常生理状态，整个测量系统也比较简单。     

Designs for Instruction, Designs for Change: Distributing Knowledge of Evidence-Based Practice

We comment on the target article by Weingardt (this issue), which discusses recent advances in instructional design and technology (IDT) and their implications for dissemination of evidence-based practices. These arguments are extended to the topic of psychological intervention design, and possibilities for new intervention structures are briefly explored. Finally, comments are offered on maintaining a careful balance between technological and social processes in the effort to promote the dissemination of innovative and evidence-based psychological procedures.     

Silicon neuron simulation with SPICE: tool for neurobiology and neural networks

The paper deals with computer simulations of ‘silicon neurons’, which are assemblies of CMOS circuits that generate the equivalents of the ionic currents and of the action potentials of real (biological) neurons. The circuit simulation program SPICE is used to simulate the generation of action potentials by a silicon neuron. Moreover, the equivalent circuits of silicon synapses are described and the behaviours of simple two- and three-neuron networks are analysed. Implications for the areas of neurobiology and formal neural networks are briefly considered.