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Guan-hua Du

Publications and source records attributed to Guan-hua Du.

10 recordsLinked to original sources
PubMed2005

Effects of gingko biloba extract on glutamate-induced [Ca2+]i changes in cultured cortical astrocytes after hypoxia/reoxygenation, H2O2 or L-glutamate injury.

AIM: To investigate glutamate-induced [Ca2+]i changes in cultured rat neonatal cortical astrocytes after hypoxia/reoxygenation, H2O2 or high concentration of L-glutamate injury. In the meantime, the effects of Gingko biloba extract (GbE) were examined. METHODS: [Ca2+]i changes in astrocytes were monitored by laser scanning confocal microscopy with the Ca2+ sensitive fluorescent probe fluo-3. RESULTS: After astrocytes were impaired by hypoxia/reoxygenation, H2O2 (50 micromol x L(-1)) or L-glutamate (0.25 mmol x L(-)), the exogenous glutamate (27 micromol x L(-1)) could not induce increase of [Ca2+]i, but decrease by (3.3 +/- 1.6)%, (81 +/- 11)% and (81 +/- 7)%, respectively. Pretreatment with GbE (10 mg x L(-1)) could not improve injured astrocytic glutamate response. But after pretreatment with GbE (100 mg x L(-1)), glutamate-induced [Ca2+]i elevation of astrocytes after hypoxia/reoxygenation, H2O2 or high concentration of L-glutamate injury were (135 +/- 98)%, (117 +/- 93)% and (89 +/- 36)%, respectively. Nimodipine (1.6 mg x L(-1)) could also reverse the abnormal response of astrocytes after different injury. CONCLUSION: Hypoxia/reoxygenation, H2O2 and high concentration of L-glutamate impaired astrocytes' response to exogenous L-glutamate, and then bidirectional communication between astrocytes and neurons could not take place. GbE could improve the abnormal responses and maintain the normal function of astroglical network. These effects support that GbE has potential beneficial actions against brain injury.

Animals↗
PubMed2005

[Effect of salidroside on mitochondria injury induced by sodium azide].

AIM: To study the protective effect of salidroside on mitochondria injury induced by sodium azide. METHODS: Human neuroblastoma SH-SY5Y cells were exposed to sodium azide with different concentration of salidroside, then cell viability was measured by thiazolyl blue (MTT) method and mitochondrial membrane potential (MMP) was detected by JC-1 method. Protective effect of salidroside against disfunction of mitochondria induced by sodium azide was detected by resazurin method. RESULTS: After exposing to 64 mmol x L(-1) sodium azide for 4 hours, cell viability and MMP of SH-SY5Y cells significantly decreased. When pretreated with salidroside, the cell damage was greatly reduced and the mitochondrial membrane potential was maintained. Furthermore, salidroside can protect function of rat brain mitochondria against damage induced by sodium azide. CONCLUSION: Salidroside was demonstrated to play an important role in improving the function of mitochondria.

Animals↗
PubMed2004

Assay of mitochondrial functions by resazurin in vitro.

AIM: To study the mechanism of resazurin as indicator of mitochondrial function and to develop a rapid and sensitive assay for measuring metabolic activity of isolated mitochondria from rat liver in vitro. METHODS: The screening was carried out on 96-well microtitre plates by monitoring fluorescence intensity of resazurin reduced by mitochondria. Experimental conditions were optimized and influences of several inhibitors on mitochondrial function were observed. RESULTS: Fluorescence intensity increased in a linear manner when the mitochondrial protein concentration from 5 to 50 microg protein per well was incubated with resazurin (5 micromol/L) during 230 min period at 37 degrees C. Edetic acid could promote the reduction of resazurin in mitochondria. The fluorescence intensity decreased greatly after pretreatment with NaN3, antimycin A, carbonyl cyanide p-trifluoromethoxyphenylhydrazone (FCCP), and oligomycin compared with the control. However, the typical complex I inhibitor, rotenone enhanced the fluorescence intensity without mitochondria. CONCLUSION: Using resazurin to determine mitochondrial function is sensitive, inexpensive and could be easily automated for high throughput screening.

Animals↗
PubMed2003

High throughput screening for intercellular adhesion molecule-1 inhibitor.

AIM: To develop a high throughput screening assay to identify inhibitors of intercellular adhesion molecule-1 (ICAM-1) expression in human umbilical vein endothelial cells (HUVEC). METHODS: ICAM-1 expression in lipopolysaccharide-stimulated endothelial cells was measured by ELISA. The cytotoxicity of the compounds was measured by MTT. RESULTS: Lipopolysaccharide (LPS) increased ICAM-1 expression in HUVEC in a concentration- and time-dependent manner. Two thousand compounds were screened and the hit rate was 1.5%. Among these 30 compounds, 24 were cytotoxic. CONCLUSION: The ELISA method was inexpensive, reproducible and suitable for high throughput primary cell assay. This assay was feasible to identify inhibitors of ICAM-1 and simultaneously discriminate the activity from the cytotoxic effects.

Cell Adhesion Molecules↗
PubMed2003

Screening of traditional Chinese remedies for SARS treatment.

The SARS epidemic is breaking out worldwide. To select suitable herbal drugs for clinical uses is important and urgent amongst the controversial treatment proposals. Nine pharmacological experimental models were used to evaluate the comprehensive efficacy of traditional Chinese remedies by cross validation in different institutes. Eight drugs were optimized for controlling different symptoms of SARS.

Animals↗
PubMed2002

[High throughput screening method of nitric oxide synthase inhibitors and enhancers].

AIM: In order to discover new inhibitors and enhancers of nitric oxide synthase (NOS), an in vitro assay to determine NOS activity was established for high throughput screening. METHODS: The activity of NOS was detected based on the change of nicotinamide-adenine dinucleotide phosphate (NADPH) concentration in the reaction system by the fluorescence density. The enzyme was prepared from bovine brain by gradient centrifugation. The reaction performed in black 96 well micro-plate with a final volume of 90 microL. Every factor which would affect the results such as the concentration of NADPH, L-arginine (L-Arg, used as substrate) and enzyme protein was optimized in different conditions. At last, 5,600 samples (compounds and extracts) were screened by the method. RESULTS: The test signal (fluorescence density) in the reaction system was influenced by many different factors such as temperature and concentration of substrates. The ideal system contains protein 1.50 mg.mL-1, L-Arg 1 mmol.L-1, NADPH 0.1 mmol.L-1 at 37 degrees C. In this method, there were about 2% samples which emit fluorescence, and about 0.5% samples which quench the fluorescence. So these samples were deleted from the sample library. The effects of these samples on activity of NOS were distributed in a normal manner. About 2% samples had potential effects on the NOS activity (including inhibitors and enhancers). CONCLUSION: The method can be performed by high throughput screening and gives the stable data, not only for inhibitors, but also for enhancers of NOS activity.

Animals↗