用荧光指示剂Fura－2测定正常和电刺激后蛙肌胞浆自由Ca~（2＋）浓度

蛙半腱肌肌束负载Ｆｕｒａ－２／ＡＭ后,可用荧光信号Ｆ３４０、３８０ｎｍ波长比值（Ｒ３４０／３８０）反映胞浆内游离Ｃａ２＋浓度（〔Ｃａ２＋〕）。利用这一技术,我们发现长时间电刺激后的骨骼肌〔Ｃａ２＋〕,高于未刺激肌,Ｒ３４０／３８０分别为１．４９±０．５４（ｎ＝１０）和１．０２±０．２６（ｎ＝１０）。加入Ｃａ２＋载体伊屋诺霉素（ｉｏｎｏｍｙｃｉｎ,１μｍｏｌ／Ｌ）后,正常肌与电刺激肌〔Ｃａ２＋〕,均上升,但刺激肌上升幅度低,持续时间短。说明电刺激至力竭后,细胞内有较多的Ｃａ２＋负载。增加细胞外Ｃａ２＋浓度至１５ｍｍｏｌ／Ｌ,〔Ｃａ２＋〕ｉ下降。而给予Ｎａ＋－Ｃａ２＋交换阻断剂奎尼丁（１０４ｍｏｌ／Ｌ）后,正常肌〔Ｃａ２＋〕ｉ上升,刺激肌〔Ｃａ２＋〕ｉ下降。结果提示：Ｎａ＋－Ｃａ２＋交换是正常骨胳肌外排Ｃａ２＋的途径之一;而长时间肌肉活动则可能使细胞膜Ｎａ＋－Ｃａ２＋交换方式改变,从而导致力竭肌〔Ｃａ２＋〕ｉ上升。     

Comparison of European and US biological indicators for ethylene oxide sterilization

Summary Biological indicators (BIs) are used to monitor ethylene oxide (EO) gas sterilization processes for medical devices. Several European and United States BIs for EO sterilization were evaluated for resistance according to both United States Pharmacopeia (USP) XXI and United Kingdom's (UK) tests for D-values. US BIs areB. subtilis var. niger spores on paper strips or disc carriers while European BIs use aluminum strips, quartz sand, or cotton yarn. Numerous BIs per run and runs per lot, as well as 2–3 different lots of BIs from each manufacturer, were examined. Both British and US BIs met their respective label claims for rates of inactivation when tested against British and USP EO test parameters, respectively. However, Danish BIs, on cotton yarn or quartz sand, were not inactivated following USP specifications during the exposure dwell times tested (600 mg L^–1 EO, 54°C, 60% RH, 0–110 min). The Danish BIs will require further testing in order for us to determine if theirB. subtilis spores are unusually resistant to EO or if the spore carrier substrates protect the spores from the sterilizing gas. In conclusion, the British and American BIs for EO sterilization are equivalent in resistance despite differences in carrier substrate, recovery conditions, calculation methods for D-values, and the labeled sterilization conditions for use.     

珠三角城市群区域生态系统服务供需均衡关系

生态系统服务供需均衡关系分析为生态系统管理提供了详实的科学基础信息。基于土地利用、气象和社会经济等多源数据,采用遥感反演、水量平衡方程、修正的通用土壤流失方程和植被净生产力模型(CASA)等方法,分别评估了1990—2015年珠三角城市群粮食供给、产水服务、固碳释氧和土壤保持服务;采用相关社会经济指标核算了生态系统服务的需求量;进而揭示了栅格、县域和市域多尺度的生态系统服务供需均衡关系及其时空演变特征。研究发现：(1)除粮食供给外,产水服务、固碳释氧和土壤保持服务呈波动性增加的趋势,增幅分别为52.2%、21.8%和73.4%;在空间上表现为中部平原地区服务水平低,低山丘陵地带高的分布特征。(2)除土壤保持服务外,粮食供给、产水服务和固碳释氧服务需求量不断增加,增幅分别为10.1%、17.5%和769.4%;中部平原地区生态系统服务需求量大,低山丘陵地带小。(3)除土壤保持和产水服务外,粮食供给、固碳释氧及综合服务供需指数不断下降,其中,2015年粮食供给和固碳释氧供需指数分别为-0.47和-0.71。研究结果可为决策者了解区域的生态系统服务供需均衡匹配状况提供科学基础信息,直接服务并...     

基于土地利用变化与生态系统服务供需的中国野生亚洲象时空迁移特征分析

2021年4月,我国15头野生亚洲象(Elephas maximus)从西双版纳一路北迁至昆明市受到了全世界的关注,分析我国野生亚洲象分布区土地利用变化、生态系统服务供需关系如何影响野生亚洲象分布,对保护亚洲象与提高当地人类福祉具有重要的意义。利用生态系统服务价值当量因子法和生态系统服务需求模型计算中国野生亚洲象分布区1990、2005、2015年生态系统服务供给价值与需求指数,通过空间标准化匹配出四种生态系统服务供需模式,探究我国野生亚洲象偏好分布的供需模式。结果表明,林地、草地和耕地是最主要的土地利用类型,1990—2015年,林地、草地和耕地的面积变化率分别为1.09%、-4.82%、-4.86%。1990、2005、2015年生态系统供给总价值分别为6108.55亿元、7434.41亿元、13973.37亿元;生态系统服务需求不断提高,整体呈现中间高,四周低的分布格局。在研究的25年内,亚洲象分布于高供给-高需求与高供给-低需求区域,且有向高供给-高需求区域迁徙的趋势。     

基于地表水与地下水分割校正的漓江流域水供给服务时空格局研究

喀斯特区域水循环过程与其他地区存在显著区别,其水供给服务也具有独特的空间分布特征。然而,目前针对喀斯特地区产水量的时空变化研究较少考虑喀斯特生态系统的特殊性,导致产水量的空间模拟结果存在一定偏差。根据喀斯特地貌形态和地下水补径排泄特征提出了一种产水量分割方法,并基于水量平衡原理建立了地表水与地下水分割校正概念模型。选取喀斯特山区典型区域漓江流域为研究区,通过上述方法校正了InVEST模型产水量模拟结果,从栅格、地貌分区和子流域3个尺度分析了漓江流域2000—2020年产水量校正前与校正后时空分布格局。研究结果表明：(1)漓江流域2000—2020年InVEST模型产水量呈现先减后增再减的趋势,水供给服务空间分布格局为北高南低。产水深度在岩溶区和非岩溶区几乎没有差异,但在岩溶区内部差异明显：裸露型岩溶区产水深度高于覆盖型和埋藏型,峰林平原产水深度高于峰丛洼地。子流域分区平均产水深度排序为漓江上游区>漓江中游区>恭城河区>荔浦河区>漓江下游区。(2)利用地表与地下水分割校正后,水供给服务空间分布格局为四周高于中部,西北部高于东南部。非岩溶区产水深度明显高于岩溶区,埋...     

黄河流域生态安全屏障防风固沙时空变化及驱动因素

黄河流域是我国重要的生态屏障和经济区,防风固沙服务及其驱动机制的研究对于筑牢黄河流域生态安全屏障具有重要意义。基于修正土壤风蚀模型(RWEQ)定量评估黄河流域2000—2018年防风固沙服务时空变化,采用相关分析和地理加权回归模型(GWR)从社会、气候、土壤、植被、地形等角度探究各驱动因素对黄河流域防风固沙服务影响的空间异质性。结果表明：(1)2000—2018年黄河流域土壤风蚀模数与单位面积防风固沙量分别以0.04 t hm^-2 a^-1和0.14 t hm^-2 a^-1的速率下降,而防风固沙保有率和植被覆盖度则分别以0.05%·a^-1和0.26%·a^-1的速率上升。(2)黄河流域土壤风蚀以微度(<2 t hm^-2 a^-1)和轻度(2—25 t hm^-2 a^-1)为主,共占研究区面积的96.28%。土壤风蚀在空间分布呈现西北高东南低的特点,而防风固沙服务高值则主要分...     

Design of a Robotized Magnetic Platform for Targeted Drug Delivery in the Cochlea

Inner ear disorders' treatment remains challenging due to anatomical barriers. Robotic assistance seems to be a promising approach to enhance inner ear treatments and, more particularly, lead to effective targeted drug delivery into the human cochlea. In this paper we present a combination of a micro-macro system that was designed and realized in order to efficiently control the navigation of magnetic nanoparticles in an open-loop scheme throughout the cochlea, considering that the magnetic particles cannot be located in real time.In order to respect the anatomical constraints, we established the characteristics that the new platform must present then proceeded to the design of the latter. The developed system is composed of a magnetic actuator that aims to guide nanoparticles into the cochlea. Mounted on a robotic manipulator, it ensures its positioning around the patient's head. The magnetic device integrates four parallelepiped-rectangle permanent magnets. Their arrangement in space, position and orientation, allows the creation of an area of convergence of magnetic forces where nanoparticles can be pushed/pulled to. To ensure the reachability of the desired orientations and positions, a 3 DOF robot based on a Remote Centre of Motion (RCM) mechanism was developed. It features three concurrent rotational joints that generate a spherical workspace around the head. The control of the latter is based on kinematic models.A prototype of this platform was realized to validate the actuation process. Both magnetic actuator and robotic manipulator were realized using an additive manufacturing approach. We also designed a virtual human head with a life-size cochlea inside. A laser was mounted on the end effector to track the positioning of the actuator. This permitted to experimentally prove the capacity of the robotic system to reach the desired positions and orientations in accordance with the medical needs.This promising robotic approach, makes it possible to overcome anatomical barriers and steer magnetic nanoparticles to a targeted location in the inner ear and, more precisely, inside the cochlea.     

A Physician's Perspective on the Incorporation of Pictograms as a Supplement to Medical Instructions in Chile: A Pilot Study

Introduction and objectivesCurrent models of health care are progressively migrating to more participatory models, where for treatment to achieve results that last over time, there must be effective communication between the patient, his or her caregivers, and health professionals. Although the use of pictograms in the context of medical instructions has been widely studied, in our country, there are no studies about their usefulness, or which set of symbols should be used by the systems. This work aims to present the first step towards the development of platforms that automatically suggest pictograms to supplement medical instructions for primary care settings in Chile.Materials and methodsIn this pilot study, we collected and analyzed the physicians' opinions on the selection of medical instructions that later will automatically be supplemented by the software that is under construction. We designed an expert validation survey using a set of 66 medical instructions with pictograms. This survey provided three rating options for each medical instruction: Not necessary (supplementing the instruction with a pictogram does not carry any value), Useful (supplementing the instruction with a pictogram may help patients to understand and remember the instruction), and Essential (supplementing the instruction with a pictogram is essential). Seventy-one physicians responded to the survey.Results22 out of 66 medical instructions were considered “essential” by >=51% of the experts, and 12 of the 66 were considered to be “useful but not essential” by >=51% of the experts.ConclusionResults of our survey validate the potential use of pictograms as a complement to better comprehension of medical instructions in our country.     

Cryopreservation of Plasmodium chabaudi. II. Cooling and warming rates

Various cooling and warming rates were investigated to determine the optimum conditions for cryopreserving the intraerythrocytic stages of Plasmodium chabaudi. Infected blood, equilibrated in 10% v/v glycerol at 37 degrees C or in 15% v/v Me2SO at 0 degree C for 10 min, was cryopreserved using cooling rates between 1 and 5100 degrees C min-1. After overnight storage in liquid nitrogen the samples were warmed at 12,000 degrees C min-1. Warming rates between 1 and 12,000 degrees C min-1 were investigated using samples previously cooled at 3600 degrees C min-1. After thawing, the glycerol and Me2SO were removed by dilution in 15% v/v glucose-supplemented phosphate-buffered saline. Survival was assayed by inoculation of groups of five mice each with 10(6) infected cells and the time taken to reach a level of 2% parasitemia estimated. The optimum cooling rate was 3600 degrees C min-1 for parasites frozen using either 10% glycerol or 15% Me2SO; the pre-2% patent periods were 0.90 and 1.01 days above control values (representing survival levels of 21 and 17.5%, respectively). The optimum warming rate was 12,000 degrees C min-1; the pre-2% patent periods were 1.01 and 1.32 days above control values, respectively (18 and 10% survival), for glycerol and Me2SO. With ethanediol (5% v/v) and sucrose (15% w/v) as cryoprotectants the optimum warming rates were also 12,000 degrees C min-1 while the optimum cooling rates were 330 and 3600 degrees C min-1, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)