Localization of trehalose in partially hydrated DOPC bilayers: insights into cryoprotective mechanisms

Trehalose, a natural disaccharide with bioprotective properties, is widely recognized for its ability to preserve biological membranes during freezing and dehydration events. Despite debate over the molecular mechanisms by which this is achieved, and that different mechanisms imply quite different distributions of trehalose molecules with respect to the bilayer, there are no direct experimental data describing the location of trehalose within lipid bilayer membrane systems during dehydration. Here, we use neutron membrane diffraction to conclusively show that the trehalose distribution in a dioleoylphosphatidylcholine (DOPC) system follows a Gaussian profile centred in the water layer between bilayers. The absence of any preference for localizing near the lipid headgroups of the bilayers indicates that the bioprotective effects of trehalose at physiologically relevant concentrations are the result of non-specific mechanisms that do not rely on direct interactions with the lipid headgroups.     

An improved cryo-jet freezing method

A new cryo-jet freezing apparatus is described that is easy to use and gives good results using a propane-butene mixture (3: 1). Our use of the freezer in the study of mouse spinal cord explant cultures is discussed. At the tissue surface, the quality of tissue preservation from freezing, followed by freeze substitution, rivals that of conventional electron microscopic methods. Certain intracellular structures are better visualized using our methods. There is no evidence of the tissue being distorted by the cryogen jet when the freezer is operated correctly. A new freeze substitution device is also discussed.     

低温生物技术在神经科学中的应用

低温生物技术的下一个热点之一是它在神经科学中的应用，本文立足于现代低温生物技术，神经科学，混沌分形等现代工程技术理论，探讨低温生物技术在神经科学上的发展趋势和应用前景，提出低温冷脉冲对钙离子通道信息传导的抑制的研究，探索阐明低温对神经调节与止痛的机理是有重要科学意义的。     

-196—+100℃高低温摄像装置低温性能实验研究

设计和研制了面向-196℃到+100℃全温区高低温工作环境的紧凑型摄像监视系统,采用真空绝热、热桥阻断和主动加热或冷却等绝热保温措施,实现了系统在目标温度范围内正常工作。当外部环境为低温工况时,在设备自身产热的基础上,调节内部电加热膜片进行热量补偿;当外部为高温工况时,通过持续进出的常温干燥氮气冷却摄像核心器件。两者可连续切换。对所设计的高低温摄像系统进行了漏热理论计算并对其实际耐高低温性能进行实验研究,结果表明该系统可胜任-196—+100℃高低温工作任务,内部感光器件表面的实际温度可控制在-30—+50℃之间。     

Temperature and cooling rate variations during cryosurgical probe testing

Cryosurgery is the destruction of tissue by freezing in situ. The design and use of cryoprobes for this duty requires a knowledge of the rate of cooling of tissue at different distances measured in different directions from the probe surface. Experiments are reported using a probe having a flat circular surface 25 mm diameter which can be cooled through a range of temperatures down to -160°C. In vitro experiments are reported for cooling water, gelatin solutions and for beef and liver tissue. In vivo tests are reported with skin/muscle of dogs. These measurements show that, contrary to current views freezing develops fairly uniformly in all directions, and heat conduction is more rapid perpendicular to the cooling surface. Further experiments using repetitive freeze/thaw cycles are also reported.     

Biological chip technology to quickly batch select optimum cryopreservation procedure

In the practices of cryobiology, selection of an optimum freeze/thawing program and an idealistic cryoprotective agent often requires rather tedious, time consuming and repetitive tests. Integrating the functions of sample preparation and viability detection, the concept of biochip technology was introduced to the field of cryopreservation, aiming at quickly finding an optimum freezing and thawing program. Prototype devices were fabricated and corresponding experimental tests were performed. It was shown that microflow-channel chip could not offer a high quality solution distribution. As an alternative, the spot-dropping chip proved to be an excellent way to load the sample quickly and reliably. Infrared thermal mapping on such a chip showed that it had a rather uniform heat transfer boundary. Applying the spot-dropping chip combined with the thermoelectric cooling device, the final output of cryopreservation of multiple samples was tested, and the optimal freeze/thawing program as well as the potentially best concentration of the cryoprotective agent was found by analyzing the results. Further, application of this technique to measure the thermo-physical properties of the cryo-protective agent was also investigated. The study demonstrated that a biochip with integrated automatic loading and inspection units opens the possibility of a massive optimization of the complex cryopreservation program in a quicker and more economical way. Translated from Cryogenics, 2006, (1): 21–26 [译自: 低温工程]     

局部组织灌注率的无损检测──表面热干扰稳态测量

组织灌注率是一个重要的生理参数，可是迄今尚缺乏一种满意的测量方法。为此目的的热学方法具有一些潜在优势，因此受到人们的重视。本文提供的表面热干扰稳态测量方法是一种无损伤测量方法，并可以实现定量测量。本文还提供了这种测量的多数计算结果，分析了探头尺寸、环境温度对测量性能曲线和测量深度的影响，得到了对仪器设计具有重要启示性的结果，制成了适用于临床的便携式测量仪，并分别利用家兔的人工定量灌注、离体的猪、牛肉和人的在体测量对本测量方法做了实验检验，得到了初步的肯定。     

A thermoelectric microscope stage for the measurement of the supercooling points of microscopic organisms

The design and construction of a thermoelectric cooling stage and its use for the determination of the supercooling points of microscopic organisms is described. Stage cooling is produced by a Peltier unit with a refrigerated circulator as a heat sink. Control is achieved by automatically comparing the temperature input to a reference ramp and varying the power input to the Peltier module accordingly.     

低温显微镜的研制

低温显微镜是低温生物医学研究中的重要工具,介绍了低温显微镜的历史和主要类型,并设计制作了一台采用液氮冷却的低温显微镜。该低温显微镜采用电子膨胀阀控制冷却介质的流量,最大升温速率可达100℃/min,最大降温速率可达50℃/min,控温精度为±1℃。