Zheng Xiaoxiang

Drug evaluations using a novel microphysiometer based on cell-based biosensors

Abstract This paper presents a novel microphysiometer based on cell-based biosensors for simultaneous measurements of several extracellular ion concentrations in living cells when treated with drugs. It can measure the extracellular acidification rate (ECAR) under the effects of the drug. Thus the relation between the cells’ metabolism and the activity of receptors can be explored, and the function of the drug can be analyzed. We used our system to measure the effects of some drugs on the nephridium and cardiac muscle cells of the suckling rat. As the microphysiometer works under regular cell culture conditions, cells can be repeatedly simulated with drugs to complete dose–response curve within a few hours. With the detection of a general parameter (extruded protons and ions), the system can be used to monitor the real-time process of the cells’ metabolism, observe the functional responses of different kinds of membrane-bound receptors and evaluate the drugs.

Modeling the Diffusion of Nitric Oxide Produced by Neuronal Cells in Brain Ischemia

Mathematical models of NO diffusion were established to investigate the role of nitric oxide produced by neuronal cells in brain ischemia. Results showed that NO synthesized at early stage of brain ischemia could diffuse to a far more distant than that of a resting state. We speculate the roles of NO produced by neuronal cells in brain ischemia might have two different effects, depending on its concentration

Advanced Measurement and Quantitative Appraise of Anisodamine on Calcium Triggered in Cardiac Myocyte

Both patch clamp and laser scanning confocal microscopy (LSCM) was applied to appraise the Anisodamines cardioprotective effects quantitatively and its mechanism were studied. MTT measurement was observed cell viability and Fluo-3/AM was utilized for real-time free calcium with LSCM; ICa,L exposed to Anisodamine was measured by whole-cell patch clamp recording technique. Our study observed that KCL-triggered calcium elevation could be decreased by Anisodamine at dose of 0.04 mmol/L and 0.08 mmol/L with the decreased value of 46.6%, 54.3% correspondingly. Further study of Anisodamine at 0.08 mmol/L showed a marked inhibitory modulation of L-type Ca2+ current density in a time-dependent manner with decreased ratio of (34.8 plusmn 7.9) % (n = 6, P < 0.01), from the value of -4.474 pA/pF to -2.882 pA/pF and accelerated Vil/2 of current inactivation curve from -14.7 mV to -28.4 mV and delayed Vil/2 of current activation curve from -15.6 mV to -9.51 mV. Our result suggests that Anisodamine conferred the cardioprotection by decreasing calcium elevation quantitatively; the likely mechanism was suggested to be responsible for inhibition of L-calcium channel

Application of overexcitation model induced by penicillin sodium in the study of inhibitory effect of sedative-hypnotic drugs

ABSTRACT Excessive release of glutamate can cause many nervous system disorders. It has been reported that when a high dose of penicillin sodium is administered into the rats brain, epilepsy, accompanied with glutamate elevation, will result. In this experiment, a low dose of penicillin sodium (1000 kIU/l) was microinjected into the rats lateral ventricle to set up an overexcitation model, in which the concentration of ipsilateral hippocampal glutamate was monitored in vivo. by microdialysis-HPLC method as an indicator of the rats excitatory state. Influences of sedative-hypnotic drugs on this model were verified by coadministration of diazepam or phenobarbital with Na-PCN intracerebroventricularly. In models, hippocampal glutamate concentration was elevated to 307% compared with its baseline level (p < 0.05), and this increase of glutamate was inhibited completely when different doses of diazepam or phenobarbital were administered (p < 0.05). The sedative effect of jujuboside A and trifluoperazine were then studied with this model. Jujuboside A (JuA) 0.1 g/l also reduced the glutamate level significantly (p < 0.05). Calmodulin antagonist trifluoperazine showed similar inhibitory effect as JuA, which may indicate that the effect of JuA is correlated with its anticalmodulin action. This model can be used to investigate the inhibitory effect of central nervous system drugs.

Effects of Puerarin on Monoamino Neurotransmitter Levels in the Striatum of Cerebral Ischemia Rats

This study was undertaken to examine the patterns of changes in extracellular fluid (ECF) dopamine (DA), orepinephrine (NE) and serotonin (5-HT) in the striatum of rats with middle cerebral artery occlusion (MCAO). The effect of Puerarin on monoamine neurotransmitter in the MCAO rats was also studied. Methods: Microdialysis was used to sample the brains extracellular space during 80 min of cerebral ischemia followed by 80 min of reperfusion. The microdialysate was measured by high performed liquid chromatography (HPLC). Results: It showed Puerarin could alleviate cerebral ischemia damage.

A Potential Excitability Was Induced by Basic Fibroblast Growth Factor during Early Differentiation of Neurons from Mouse Embryonic Stem Cells in vitro

We report that basic fibroblast growth factor (bFGF) induces the release of glutamate in ES-derived neurons during early stages of differentiation. Changes of Ca2+ concentration labeled by fluorescence intensity occurred in response to minimal concentrations of glutamate. The Ca2+ concentration was changed more rapidly by bFGF than by glutamate during the early stages of differentiation of ES-derived neurons. High concentrations of the inhibitor MK801, an N-methyl-D-aspartate (NMDA) receptor antagonist applied before bFGF stimulation caused a dramatic decrease of fluorescence intensity in neurons derived from both hippocampal and ES cells. These results showed that bFGF induces glutamate release and an increase of [Ca2+] in neurons during early stages of differentiation, and that the increase of [Ca2+] can be inhibited by MK801. Therefore, we concluded that bFGF serves not only as a neurotrophin but also as a stimulator of excitability during the differentiation of ES cells into neurons

Studies of selective ion-sensitive microelectrode technique for the detection of neurotransmitter in vivo

The neurotransmitters such as acetylcholine/choline (Ach/ch), serotonin and dopamine play very important roles in the course of neurological diseases. Traditional methods used in the detection of these neurotransmitters have enzymatic and radiochemical methods, fluorescence spectroscopy, gas chromatography, high performance liquid chromatography, thin layer chromatography etc. But these methods cannot be used in the direct and continuous detection of neurotransmitter activity in a single cell. Here, a new ion-selective microelectrode technique has been developed. The advantage of the ion-sensitive microelectrode technique is in its very high spatial resolution, by which some interesting ion activity inside and outside the living cells can be monitored continuously for a relatively long time without great damage to the living cells. All these virtues of this technique force the authors to develop some new ion-sensitive microelectrode especially for acetylcholine/choline, serotonin, histamine and dopamine. The results obtained showed that the technique could be used successfully in the detection of neurotransmitters at the cellular level, and the technique has promising prospects in the field of neuroscience.

Cytocompatibility of new-type sulfonated polymer surfaces

Human umbilical vein endothelial cells (HUVEC) are chosen to test the cytocompatibility of the modified polymer surfaces and study the cell-material surface interaction with an attempt to develop new-type biofunctional polymer surfaces. A new-type sulphonated polymer surface has been prepared by a solution technique and the sulfonated polymer surface obtained has shown a good antithrombogenic property by in vitro clotting time evaluation and platelet adhesion experiments. Sulfonated SPEO is obtained by the reaction of stearic polyethylene oxide (SPEO) and 1,3-propane sulfone. Polystyrene (PS) is used as model polymer. The sulfonated polymer surfaces (SS surfaces) are obtained by the sulfonated SPEO (SSPEO) THF/water solution treatment. The modified PS surfaces are characterized by SEM and ESCA. The EC adhesion and proliferation experiments are done on the modified surfaces by red cell counting, and the morphology of the adhered ECs is observed by SEM. The results show that SS surfaces are of good cytocompatibility. The reason is attributed to the combined influence of functional groups SO/sub 3//sup -/ and flexible PEO chains.