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
The distribution of heavy metals in earthworms has been widely studied, highlighting the importance of the fate of these metals.However, little information is available on the distribution of hydrophobic organic conta...The distribution of heavy metals in earthworms has been widely studied, highlighting the importance of the fate of these metals.However, little information is available on the distribution of hydrophobic organic contaminants(HOCs) within earthworms. The aim of this study was to propose a hierarchic method to study the distribution of phenanthrene(PHE), a typical HOC, in Eisenia fetida at several levels: sub-organism(pre-clitellum, clitellum and post-clitellum), tissue(body wall, gut and body fluid) and subcellular(intracellular and extracellular fractions). Earthworms were incubated in the soils amended with low(LC, 10 mg kg-1) and high concentrations(HC, 50 mg kg-1) of PHE and sampled at different time intervals. At the sub-organism level, the distribution of PHE was homogeneous among the sub-organism fractions in the LC treatment but heterogeneous in the HC treatment and gradually reached the following form of post-clitellum ≈ clitellum > pre-clitellum. The uptake and elimination kinetics of PHE in the sub-organism were well described by a one-compartment model. At the tissue level, the concentration of PHE followed the order of gut > body fluid >body wall; while at the subcellular level, the concentration of PHE in the extracellular fraction was 1.23 to 4.68 times higher than that in the intracellular fraction. Therefore, the simple circulatory system of earthworms may account for the PHE distribution at the sub-organism level. Partition pathways(passive diffusion) of PHE between the body wall, body fluid and gut as well as the processes of PHE entrance into the inner cellular compartment via passive diffusion were experimentally supported.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.
基金Supported by the National Natural Science Foundation of China(No.41101292)
文摘The distribution of heavy metals in earthworms has been widely studied, highlighting the importance of the fate of these metals.However, little information is available on the distribution of hydrophobic organic contaminants(HOCs) within earthworms. The aim of this study was to propose a hierarchic method to study the distribution of phenanthrene(PHE), a typical HOC, in Eisenia fetida at several levels: sub-organism(pre-clitellum, clitellum and post-clitellum), tissue(body wall, gut and body fluid) and subcellular(intracellular and extracellular fractions). Earthworms were incubated in the soils amended with low(LC, 10 mg kg-1) and high concentrations(HC, 50 mg kg-1) of PHE and sampled at different time intervals. At the sub-organism level, the distribution of PHE was homogeneous among the sub-organism fractions in the LC treatment but heterogeneous in the HC treatment and gradually reached the following form of post-clitellum ≈ clitellum > pre-clitellum. The uptake and elimination kinetics of PHE in the sub-organism were well described by a one-compartment model. At the tissue level, the concentration of PHE followed the order of gut > body fluid >body wall; while at the subcellular level, the concentration of PHE in the extracellular fraction was 1.23 to 4.68 times higher than that in the intracellular fraction. Therefore, the simple circulatory system of earthworms may account for the PHE distribution at the sub-organism level. Partition pathways(passive diffusion) of PHE between the body wall, body fluid and gut as well as the processes of PHE entrance into the inner cellular compartment via passive diffusion were experimentally supported.
