Biomedical subjects

Xiao-xiang Zheng

Publications and source records attributed to Xiao-xiang Zheng.

8 recordsLinked to original sources

PubMed2006

A preadipocyte differentiation assay as a method for screening potential anti-type II diabetes drugs from herbal extracts.

A cell-based method for screening drug candidates from herbal extracts that have possible anti-type II diabetic effects was established. The differentiation of preadipocytes into adipocytes was used as a sensitive primary indicator of a drug's potential effect on type II diabetes. We established a quantitative method by using a computer image analysis system for assessing the morphological alterations. The assay was validated by screening compounds extracted from Chinese herbs and the known drug rosiglitazone for their capability of modulating PPARgamma gene expression and glucose uptake by adipocytes. Two drug candidates having possible anti-type II diabetic effects were identified.

Adipocytes↗

PubMed2006

Effects of astragaloside IV on pathogenesis of metabolic syndrome in vitro.

AIM: To investigate the diverse pharmacological actions of astragaloside IV from the perspective of metabolic syndrome, and to investigate the effect of the drug on the pathogenesis of metabolic syndrome. METHODS: Adipogenesis was used as an indicator of the effect of astragaloside IV on preadipocyte differentiation, and was measured by using an oil red O assay. Glucose uptake was determined by measuring the transport of [2-(3)H]-deoxyglucose into the cells. The concentrations of peroxisome proliferator-activated receptor-gamma (PPARgamma) and aP2 mRNA were determined by using reverse transcription-polymerase chain reaction. Apoptosis and viability loss of endothelial cells were detected by using flow cytometry and the WST-1 assay, respectively. Intracellular free Ca2+ was labeled with Fluo-3 AM and measured by using a laser scanning confocal microscope. RESULTS: Astragaloside IV can significantly potentiate insulin-induced preadipocyte differentiation at concentrations of 3, 10, and 30 microg/mL, improve high glucose-induced insulin resistance in adipocytes at a concentration of 30 microg/mL, and prevent tumor necrosis factor (TNF)-alpha-induced apoptosis and viability loss at concentrations of 10 and 30 microg/mL, and 30 microg/mL, respectively, in endothelial cells. Furthermore, we found that these effects were partly due to the promotion of PPARgamma expression and to the inhibition of abnormal TNF-alpha-induced intracellular free Ca(2+) accumulation in endothelial cells. CONCLUSION: The diverse pharmacological actions of astragaloside IV can all be linked to metabolic syndrome pathogenesis. Our study provides a new insight into the mechanism by which astragaloside IV exerts its effect.

Adipocytes↗

PubMed2006

[Effect of dialysis time in vivo on recovery of amino acids for micro-dialysis probe].

OBJECTIVE: To investigate the variety of vitro recovery of amino acids for microdialysis probe after different dialysis time in vivo. METHODS: Probes were dialyzed in the amino acids standard solutions with microdialysis system,amino acid standard solutions and the microdialysate of probe were detected by the method of precolumn derivation with HPLC-RF. RESULT: After using different time of probe made by regenerated cellulose membrane, the vitro recoveries of Asp, Glu and GABA were not completely same (Asp: F=19.669, P=0.000; Glu: F=103.955, P=0.000; GABA: F=3.454, P=0.040); while the vitro recovery of Tau had no obvious difference(F=2.001, P=0.152). After using 6 h in vivo, recovery remain percentage (RRP) of Asp, Glu,Tau and GABA was 64.34 %, 67.36%, 103.11 % and 98.23 %, respectively, the recoveries of Asp, Glu decreased obviously (Asp: P < 0.01,Glu: P <0.05). After using 12 h in vivo, the RRP of Asp, Glu, Tau and GABA was 43.44 %, 24.42%, 77.45 % and 67.36 %, respectively, the recoveries of Asp, Glu and GABA decreased obviously (Asp: P < 0.001, Glu: P < 0.001, GABA: P < 0.05). After using 24 h in vivo, the RRP of Asp, Glu,Tau and GABA was 36.26 %, 12.24 %, 89.48 % and 71.35 %, respectively, the recoveries of Asp, Glu, GABA decreased obviously (Asp: P < 0.0001, Glu: P < 0.0001, GABA: P < 0.01). CONCLUSION: Dialysis in vivo could lead to the decline of recovery of probe, the decline is more obvious after longer dialysis. So when making brain dialysis experiments, the use time of probe should not be too long. To improve the validity of data, some calibration should be made on the recoveries of probe.

Amino Acids↗

PubMed2005

Intracellular-free calcium dynamics and F-actin alteration in the formation of macrophage foam cells.

The formation of macrophage foam cells, which is the key event in atherosclerosis, occurs by the uptake of oxidized low-density lipoprotein (Ox-LDL) via the scavenger receptor (CD36) pathway. Ca(2+) plays an important role in atherosclerosis. However, in the spatiotemporal view, the correlation between kinetic changes of intracellular-free calcium ([Ca(2+)](i)) and the cellular dysfunctions in the formation of macrophage foam cells has not yet been studied in detail. By the use of confocal laser scanning microscope and flow cytometer, we have detected Ca(2+) dynamics, the assembly of F-actin, and the expression of CD36 under the exposure of U937-derived macrophages to Ox-LDL. The uptake of Ox-LDL significantly increased [Ca(2+)](i) in U937-derived macrophages in both acute and chronic treatments (P<0.01). In particular, the increases of the induced [Ca(2+)](i) were different in the presence or absence of extracellular Ca(2+) under acute exposure. A time-dependent rise in F-actin assembly and CD36 expression at 12 and 24h was induced, respectively, by Ox-LDL. The spatiotemporal increases of [Ca(2+)](i) induced by Ox-LDL probably have the key effect on the early phrase in the formation of macrophage foam cells.

Actins↗

PubMed2005

Regulative effects of hawthorn leave flavonoids on cytotoxicity, NO and Ca2+ in hypoxia-treated human umbilical vein endothelial cells.

OBJECTIVE: To evaluate the potential effect of HLF (Hawthorn leave flavonoids, w/w, 80% flavonoids) against thrombus formation, effect of HLF on hypoxia-treated human umbilical vein endothelial cell (HUVECs) was studied. METHOD: The levels of cytotoxicity and NO upon HUVECs were studied by flow cytometry. Moreover, the level of calcium ion in HUVECs was examined through laser scanning confocal microscopy. RESULT: Data from this study showed that HLF at concentrations of 5 micrograms/ml and 10 micrograms/ml decreased the cytotoxicity of hypoxia to HUVECs (P<0.05, P<0.01). The intracellular levels of NO and calcium ion were downregulated by HLF at concentrations of 5 micrograms/ml (P<0.01; P<0.01) and 10 micrograms/ml (vs control, P<0.01; P<0.01) too. CONCLUSION: Results observed suggest that HLF protect HUVECs from hypoxia partly through its regulative effect on NO and calcium ion levels.

Calcium↗

PubMed2004

[Effects of L-tetrahydropalmatine on concentrations of neurotransmitter amino acids in mice with cerebral ischemia].

OBJECTIVE: To observe the effects of L-tetrahydropalmatine (L-THP) on concentrations of neurotransmitter amino acids in mice with cerebral ischemia and to discuss the mechanisms of L-THP in tyreating cerebral ischemia. METHOD: Mice were randomly divided into six groups: control group, cerebral ischemia group, L-THP treated group (doses were 14, 28, 56 mg x kg(-1) respectively) and Ginkgo biloba extract treated group. Concentrations of Glu and GABA were determined by HPLC. RESULT: Compared with control group, Glu and GABA in mice with cerebral ischemia were much higher. The ratio of Glu/GABA increased significantly. L-THP markedly reduced the concentrations of Glu and the ratio of Glu/GABA in mice with cerebral ischemia. CONCLUSION: Decrease in Glu concertration and ratio of Glu/GABA may be one of the mechanisms of L-THP in treating cerebral ischemia.

Animals↗

PubMed2004

[An interactive volume rendering algorithm for laser scanning confocal microscope data].

OBJECTIVE: To satisfy different observational demands, a real-time interactive volume rendering for laser scanning confocal microscope (LSCM) image was realized on the PC. METHOD: An interactive transfer function was proposed through analyzing optical properties of LSCM image, so that the users can enroll in exploring the LSCM data set by altering rendering parameters. The texture mapping based on visualization method is adopted to realize real-time 3D reconstruction. RESULT: The algorithm was realized on the common PC. All 3D reconstruction results, which fulfills various demands, was obtained by the above algorithm with LSCM data set sized 256 x 256 x 40 pixels. In the process of reconstruction, the object could be re-rendered at a rate of 10 frames per second when the rendering parameters were adjusted. CONCLUSION: Different from the traditional algorithms, the one we demonstrate here is able to offer a real-time environment on the PC and to get the 3D reconstruction results, thus easily achieve diverse observational mapping.

Algorithms↗

PubMed2002

[A study of complexity and power spectrum of cortical EEG and hippocampal potential in rats under different behavioral states].

Objective. To study the complexity and the power spectrum of cortical EEG and hippocampal potential in rats under waking and sleep states. Method. Cortical EEG and hippocampal potential were collected by implanted electrodes in freely moving rats. Algorithmic complexity (Kc), approximate entropy (ApEn), power spectral density (PSD) and gravity frequency of PSD of the potential waves were calculated. Result. The complexity of hippocampal potential was higher than that of cortical EEG under every state. The complexity of cortical EEG was lowest under the state of non rapid eye movement (NREM) sleep. The complexity of hippocampal potential was highest under waking state. The total power of both potentials in 0.5- 30 Hz frequency band showed their highest values under NREM state. Conclusion. The values of Kc and ApEn are closely related to the distributions of PSD. When there are evident peaks in PSD, the complexities of signals will decrease. The complexities may be used to distinguish the difference between cortical EEG and hippocampal potential, or large differences between the same kind of potentials under different behavioral states.

Animals↗