Transport of alpha-aminoisobutyric acid (AIB) from blood to brain in pentobarbital-anesthetized rats was examined using in situ perfusion. In situ perfusion with washed sheep red blood cells allowed ...the precise control of the composition of the perfusate that was necessary for a detailed examination of the transport of AIB. Retrograde perfusion at 4 ml/min through the left external carotid artery with oxygenated, artificial blood (hematocrit = 0.3) maintained a normal electroencephelogram during a 10 min experiment. The perfusate cerebral blood flow, at a value of 1.2 +/- 0.1 ml/g/min, and the perfusate cerebral plasma volume, at a value of 5.4 +/- 1.9 microliter/g, in the left frontal cortex were within the range of reported in vivo values. The in situ PS product for AIB (3.8 +/- 0.4 microliter/g/min) was higher than the value observed in vivo. AIB uptake was reduced to the in vivo value by 2 mM phenylalanine (1.3 +/- 0.3 microliter/g/min) and equally well by a mixture of neutral amino acids at their normal plasma concentrations but was unaffected by 2 mM methyl-AIB or removal of sodium from the perfusate. A kinetic analysis showed that the apparent Ki for phenylalanine inhibition of AIB transport was 19.8 +/- 4.9 microM. Thus, although AIB has affinity for the large neutral amino acid carrier in the blood-brain barrier, brain uptake by this mechanism in vivo is negligible due to competition by other amino acids in the plasma.
To study the performance of chitosan nanoparticles systematically, we characterized MMA, chitosan and synthesized chitosan nanoparticles by Raman spectroscopy. Through analyzing the characteristic ...peaks of each substance, we found MMA grafted chitosan by opening its carbon-carbon double bond. So Raman spectroscopy is a very effective way in terms of the characterization of nanomaterials .
The heterogeneous lattice model is presented to simulate the behaviors of concrete, in which the concrete is regarded as random medium and the stochastic damage constitutive model is proposed. The ...parameters of the stochastic damage constitutive is identified compared with the experiment results of concrete under uniaxial tension and uniaxial compression.
A Micro-Cell Size Dependent Damage Law of Concrete Ren, Xiao Dan; Li, Jie; Liang, Shi Xue
Applied Mechanics and Materials,
08/2015, Volume:
784, Issue:
Damage Mechanics: Theory, Computation and Practice
Journal Article
Peer reviewed
A micro-cell size dependent damage law is proposed by the multi-scale damage representation to remedy the mesh sensitivities involving in the numerical simulations. The homogenization based ...multi-scale damage representation is firstly introduced in obtaining the macro-damage evolution from micro-cell analysis. Then, the micro-cells with different sizes are generated and the corresponding simulations are given. Based on the simulation results, we define the micro-cell size dependent damage law. Finally, the accuracy and efficiency of the proposed damage law are verified by the notched beam simulation results.
This communication demonstrates the feasibility of the gel-clot method for the analysis of bacterial endotoxins in water extracts of perfluorocarbon which is a water insoluble liquid medical device. ...Perfluorocarbon （10 mL） was shaken with 10 mL water for 15 min at 2000 r/min and the endotoxin present was extracted to the aqueous phase without interference inhibition/enhancement of the product and the recovery of endotoxin added to perfluorocarbon was determined, A validation study confirmed that endotoxins presented in perfluorocarbon pass over into the aqueous phase at concentrations of 20, 10 and 5EU/mL with recoveries from 86.8% to 96.8%. Therefore, the gel-clot test is suitable for detecting bacterial endotoxins in perfluorocarbon which is a water insoluble medical device.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The SAR and pharmacological profile of a series of BCATc inhibitors is described.
The inhibition of the cytosolic isoenzyme BCAT that is expressed specifically in neuronal tissue is likely to be ...useful for the treatment of neurodegenerative and other neurological disorders where glutamatergic mechanisms are implicated. Compound
2 exhibited an IC
50 of 0.8
μM in the hBCATc assays; it is an active and selective inhibitor. Inhibitor
2 also blocked calcium influx into neuronal cells following inhibition of glutamate uptake, and demonstrated neuroprotective efficacy in vivo. SAR, pharmacology, and the crystal structure of hBCATc with inhibitor
2 are described.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Direct intracerebral injection of recombinant adenoviral vectors within the brain parenchyma or the ventricular system results in a limited volume of distribution of virus, as demonstrated by ...transgene expression. Global delivery to the central nervous system may increase the use of these vectors but only if the viral vectors can cross the blood-brain barrier and result in transduction of the underlying cells. This short-term study examines whether osmotic disruption with mannitol can result in sufficient opening of the vascular endothelium to allow for passage of replication-defective adenovirus containing the Escherichia coli beta-galactosidase gene (lacZ). Virus was injected into the carotid artery of rats after blood-brain barrier disruption with intracarotid hypertonic mannitol, and the animals were killed and analyzed after 4 days. Histochemical analysis and electron microscopy confirmed expression of the E. coli lacZ gene in the pericapillary astrocytes of the ipsilateral cerebral cortex and deep grey matter. Furthermore, the extent of gene transfer and expression correlated with the degree of barrier opening, as measured by Evans blue staining. Transgene expression was not seen in control animals that received intracarotid saline before recombinant virus injection. These data demonstrate, for the first time, that blood-brain barrier disruption can allow for the delivery of functional viral vectors to the central nervous system.
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