The nature of brain interstitial fluid （ISF） has long been a subject of controversy. Most of the previous studies on brain ISF were carded out in vitro. In the present study, a novel method was developed to characte...The nature of brain interstitial fluid （ISF） has long been a subject of controversy. Most of the previous studies on brain ISF were carded out in vitro. In the present study, a novel method was developed to characterize ISF in the living rat brain by magnetic resonance （MR） imaging using gadolinium-diethylenetriaminepentaacetic acid （Gd-DTPA） as a tracer. Sprague Dawley rats （n=8） were subjected to MR scanning before and after the introduction of Gd-DTPA into the caudate nucleus. A one-way drainage of brain ISF was demonstrated on the dynamic MR images. According to the traditional diffusion model, the diffusion and clearance rate constants of the tracer within brain extracellular space （ECS） were derived as （3.38±1.07）×10^-4 mm2 s^-1 and （7.60±4.18）×10^-5 s^-1. Both diffusion and bulk flow contributed to the drainage of ISF from the caudate nucleus, which demonstrated an ISF-cerebrospinal fluid confluence in the subarachnoid space at the lateral and ventral surface of the brain cortex at 3 h after the injection. By using this newly developed method, the brain ECS and ISF can be quantitatively measured simultaneously in the living brain, which will enhance the understanding of ISF and improve the efficiency of drug therapy via the brain interstitium.展开更多
Using electron spin resonance (ESR) spin labeling technique, we have studied the conformation of sulfhydryl groups(-SH) binding sites in membrane proteins and membrane fluidity of red blood cells (RBCs) from two group...Using electron spin resonance (ESR) spin labeling technique, we have studied the conformation of sulfhydryl groups(-SH) binding sites in membrane proteins and membrane fluidity of red blood cells (RBCs) from two groups of patients with anemia of chronic renal failure (ACRF). One of the groups is composed of patients who were untreated with recombinant human erythropoietin(r-HuEPO), and the other is composed of patients who were treated with r-HuEPO. The results indicated: 1) the conformation of SH group binding site in RBC membrane proteins from former group was different from those of health people. 2)the fluidity in the region near the surface of RBC membrane from former group was lower than those of healthy people. 3) However, the above biophysical properties of RBC membrane from later group were normal. We concluded that RBC membrane in patients with ACRF was abnormal, and the treatment of r-HuEPO may promote the production of normal RBCs, thus ameliorate the biophysical properties of RBCs from the patients with ACRF.展开更多
This study assesses surface urban heat island (UHI) and its associated surface physical characteristics using remote sensing approaches. TERRA/MODIS images acquired in 2005 in three different seasons were selected to ...This study assesses surface urban heat island (UHI) and its associated surface physical characteristics using remote sensing approaches. TERRA/MODIS images acquired in 2005 in three different seasons were selected to generate land surface tem-perature and surface characteristics for the Changsha-Zhuzhou-Xiangtan metropolitan area in China. The intensity of urban heat is-land effects and its seasonal variations were examined. The result showed that UHI effects were significant both in the summer and the spring. Land surface temperatures in the city were 8 ℃ to 10℃ warmer than those in surrounding rural areas in the spring and the summer seasons. Although UHI effects exist in winter, they are not significant. Land surface temperature in the city was 4℃ warmer than that in surrounding rural areas in winter. This study uses normalized difference vegetation index (NDVI) and normal-ized difference built-up index (NDBI) as indicators of surface physical characteristics and investigates the relationship among land surface temperature (LST), NDVI and NDBI. The results from this study indicate that, while the relationship between LST and NDVI changes in different seasons, there is a strong positive linear relationship between NDBI and LST for all seasons. The amount of slope and intercept of the linear relationship between NDBI and LST can indicate the magnitude of UHI for different seasons. This finding suggests that NDBI provides an alternative physical indicator for analyzing LST quantitatively over different seasons, and therefore providing a useful way to study UHI effects using remote sensing.展开更多
目的:观察有氧运动对大鼠脑动脉平滑肌细胞(SMC)的大电导钙激活钾通道(BKCa)生物物理特性的影响,为运动有效预防脑血管疾病的细胞学机制提供实验依据。方法:8周龄雄性Wistar大鼠20只,随机分为两组,安静对照组(SED)和运动组(EX)。运动组...目的:观察有氧运动对大鼠脑动脉平滑肌细胞(SMC)的大电导钙激活钾通道(BKCa)生物物理特性的影响,为运动有效预防脑血管疾病的细胞学机制提供实验依据。方法:8周龄雄性Wistar大鼠20只,随机分为两组,安静对照组(SED)和运动组(EX)。运动组进行12周跑台运动(20 m/min,60 min/d,5 d/w)。12周后,取脑动脉,经酶消化法获得单个脑动脉SMC。采用膜片钳单通道内面向外记录模式,观察各组BKCa通道的生物物理特性。结果:1)本实验中BKCa的单通道电导为221.8±6.1p S(n=8),记录电流反转电位接近0 m V,无整流现象,均符合BKCa单通道特征;2)12周有氧运动使BKCa通道活性提高:钳制电位+40 m V,[Ca2+]i为1μM时,SED和EX组BKCa通道平均开放概率分别为0.28±0.02和0.78±0.07 p S 3)有氧运动使BKCa通道电压依赖性增强:[Ca2+]i为1μM时,SED和EX组开放概率-电压曲线左移,V1/2分别为48.09±3.27 m V和26.57±3.17 m V;4)有氧运动使BKCa通道钙敏感性增强:膜电位+40 m V下,SED和EX组Po-[Ca2+]i曲线左移,Kd值分别为2.80±0.09μM和0.35±0.09μM;5)运动组大鼠BKCa通道平均开放时间(To)增大,平均关闭时间(Tc)缩短,开放时间常数(τO)增大,关闭时间常数(τC)减小,提示有氧运动使通道更易开放且更难关闭。结论:长期规律性有氧运动能改变大鼠SMC的BKCa通道门控特性,使其活性增强,这可能是运动改善脑血管舒缩功能,增强脑动脉供血的重要机制之一。展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 30972811, 81171080 and 81071148)the Twelfth Five-year Plan for National Science and Technology of China (Grant No.2012BAI15B009)
文摘The nature of brain interstitial fluid （ISF） has long been a subject of controversy. Most of the previous studies on brain ISF were carded out in vitro. In the present study, a novel method was developed to characterize ISF in the living rat brain by magnetic resonance （MR） imaging using gadolinium-diethylenetriaminepentaacetic acid （Gd-DTPA） as a tracer. Sprague Dawley rats （n=8） were subjected to MR scanning before and after the introduction of Gd-DTPA into the caudate nucleus. A one-way drainage of brain ISF was demonstrated on the dynamic MR images. According to the traditional diffusion model, the diffusion and clearance rate constants of the tracer within brain extracellular space （ECS） were derived as （3.38±1.07）×10^-4 mm2 s^-1 and （7.60±4.18）×10^-5 s^-1. Both diffusion and bulk flow contributed to the drainage of ISF from the caudate nucleus, which demonstrated an ISF-cerebrospinal fluid confluence in the subarachnoid space at the lateral and ventral surface of the brain cortex at 3 h after the injection. By using this newly developed method, the brain ECS and ISF can be quantitatively measured simultaneously in the living brain, which will enhance the understanding of ISF and improve the efficiency of drug therapy via the brain interstitium.
文摘Using electron spin resonance (ESR) spin labeling technique, we have studied the conformation of sulfhydryl groups(-SH) binding sites in membrane proteins and membrane fluidity of red blood cells (RBCs) from two groups of patients with anemia of chronic renal failure (ACRF). One of the groups is composed of patients who were untreated with recombinant human erythropoietin(r-HuEPO), and the other is composed of patients who were treated with r-HuEPO. The results indicated: 1) the conformation of SH group binding site in RBC membrane proteins from former group was different from those of health people. 2)the fluidity in the region near the surface of RBC membrane from former group was lower than those of healthy people. 3) However, the above biophysical properties of RBC membrane from later group were normal. We concluded that RBC membrane in patients with ACRF was abnormal, and the treatment of r-HuEPO may promote the production of normal RBCs, thus ameliorate the biophysical properties of RBCs from the patients with ACRF.
基金Supported by the National Natural Science Foundation of China (No.40771198)the Hunan Provincial Natural Science Foundation of China (No.08JJ6023)
文摘This study assesses surface urban heat island (UHI) and its associated surface physical characteristics using remote sensing approaches. TERRA/MODIS images acquired in 2005 in three different seasons were selected to generate land surface tem-perature and surface characteristics for the Changsha-Zhuzhou-Xiangtan metropolitan area in China. The intensity of urban heat is-land effects and its seasonal variations were examined. The result showed that UHI effects were significant both in the summer and the spring. Land surface temperatures in the city were 8 ℃ to 10℃ warmer than those in surrounding rural areas in the spring and the summer seasons. Although UHI effects exist in winter, they are not significant. Land surface temperature in the city was 4℃ warmer than that in surrounding rural areas in winter. This study uses normalized difference vegetation index (NDVI) and normal-ized difference built-up index (NDBI) as indicators of surface physical characteristics and investigates the relationship among land surface temperature (LST), NDVI and NDBI. The results from this study indicate that, while the relationship between LST and NDVI changes in different seasons, there is a strong positive linear relationship between NDBI and LST for all seasons. The amount of slope and intercept of the linear relationship between NDBI and LST can indicate the magnitude of UHI for different seasons. This finding suggests that NDBI provides an alternative physical indicator for analyzing LST quantitatively over different seasons, and therefore providing a useful way to study UHI effects using remote sensing.
文摘目的:观察有氧运动对大鼠脑动脉平滑肌细胞(SMC)的大电导钙激活钾通道(BKCa)生物物理特性的影响,为运动有效预防脑血管疾病的细胞学机制提供实验依据。方法:8周龄雄性Wistar大鼠20只,随机分为两组,安静对照组(SED)和运动组(EX)。运动组进行12周跑台运动(20 m/min,60 min/d,5 d/w)。12周后,取脑动脉,经酶消化法获得单个脑动脉SMC。采用膜片钳单通道内面向外记录模式,观察各组BKCa通道的生物物理特性。结果:1)本实验中BKCa的单通道电导为221.8±6.1p S(n=8),记录电流反转电位接近0 m V,无整流现象,均符合BKCa单通道特征;2)12周有氧运动使BKCa通道活性提高:钳制电位+40 m V,[Ca2+]i为1μM时,SED和EX组BKCa通道平均开放概率分别为0.28±0.02和0.78±0.07 p S 3)有氧运动使BKCa通道电压依赖性增强:[Ca2+]i为1μM时,SED和EX组开放概率-电压曲线左移,V1/2分别为48.09±3.27 m V和26.57±3.17 m V;4)有氧运动使BKCa通道钙敏感性增强:膜电位+40 m V下,SED和EX组Po-[Ca2+]i曲线左移,Kd值分别为2.80±0.09μM和0.35±0.09μM;5)运动组大鼠BKCa通道平均开放时间(To)增大,平均关闭时间(Tc)缩短,开放时间常数(τO)增大,关闭时间常数(τC)减小,提示有氧运动使通道更易开放且更难关闭。结论:长期规律性有氧运动能改变大鼠SMC的BKCa通道门控特性,使其活性增强,这可能是运动改善脑血管舒缩功能,增强脑动脉供血的重要机制之一。
