Biomedical subjects

Xiaoxiang Zheng

Publications and source records attributed to Xiaoxiang Zheng.

18 recordsLinked to original sources

PubMed2006

A study of the neuroprotective effect of the phenolic glucoside gastrodin during cerebral ischemia in vivo and in vitro.

The phenolic glucoside gastrodin (Gas) is a main component extracted from the rhizome of Gastrodia elata, a Chinese herbal medicine, which has long been used for treating dizziness, epilepsy, stroke and dementia. In this study, we investigated the neuroprotective effects of Gas on cerebral ischemic injury in rats caused by transient middle cerebral arterial occlusion (MCAO), oxygen/glucose deprivation (OGD) and glutamate-induced injury in cultured rat hippocampal neurons. Additionally, the effects of Gas on the extracellular glutamate level and changes in intracellular Ca (2+) and the generation of nitric oxide (NO) were examined in cultured hippocampal neurons subjected to OGD in vitro. The results showed that the high dose of Gas (100 mg/kg) markedly decreased the infarct volume and edema volume, and improved the neurological functions after MCAO. Gas treatment (15 microg/mL, 30 microg/mL) also significantly inhibited OGD- and glutamate-induced neuronal cell death and reduced the extracellular glutamate level following OGD. Moreover, Gas treatment significantly inhibited the OGD-induced Ca (2+) and NO increases. In conclusion, the present study indicates that Gas has a neuroprotective action.

Animals↗

PubMed2006

Artificial neural network based model for cardiovascular risk stratification in hypertension.

This study was to develop an objective method to stratify cardiovascular risk in hypertension. Stratification for cardiovascular risk is crucial in deciding treatment strategy for hypertension but has yielded undesirable results in clinic due to its low accuracy which is caused by physicians' subjective experience and the uncertainty of patients' statements. Our model proposed herein overcomes these disadvantages by applying artificial neural network based on a classic back propagation net. The model input is derived from the clinical investigation. The target output is the stratification level of total cardiovascular risk, which is learned from the guidelines of hypertension treatment. Study in 348 normotensive and hypertensive subjects showed that the results of model stratification are consistent with the standard stratification suggested by hypertension guidelines in 81.61% cases. The results confirm the accuracy of the model and demonstrate its ability in risk evaluation for hypertension.

Algorithms↗

PubMed2006

Decreasing expression of alpha1C calcium L-type channel subunit mRNA in rat ventricular myocytes upon manganese exposure.

Manganese is an essential trace element found in many enzymes. As it is the case of many essential trace elements, excessive level of manganese is toxic. It has been proven that excessive manganese could cause heart problems. In order to understand the mechanism of manganese toxicity in the heart, the effects of manganese on isolated rat ventricular myocytes were studied. The L-type calcium channel current was measured by whole-cell patch clamp recording mode. In the electrophysiology experiments, both 50 microM Mn2+ and 100 microM Mn2+ could effectively decrease the channel current amplitude density by 35.7% and 68.2%, respectively. Moreover, Mn2+ shifted the steady-state activation curve toward more positive potential and the steady-state inactivation curve toward more negative potential. Investigation by RT-PCR showed that the mRNA expression of alpha1C/Cav1.2 treated with manganese was decreased depending on its concentration, while the mRNA expression of alpha1D/Cav1.3 was almost unchanged. Fluo-3/AM was utilized for real-time free calcium scanning with laser scanning confocal microscopy (LSCM), and the results showed that Mn2+ could elicit a slow and continuous increase of [Ca2+]i in a concentration-dependent manner. These results have suggested that manganese could interfere with the function of the L-type calcium channel, downregulate the mRNA expression of alpha1C/Cav1.2, and thus causing long-lasting molecular changes of L-type calcium channel which have probably been triggered by overloading of calcium in myocytes.

Animals↗

PubMed2006

Bioassay-guided isolation of antiatherosclerotic phytochemicals from Artocarpus altilis.

The cytoprotective effects of various solvent extracts of Artocarpus altilis (Parkinson) Fosberg were evaluated. The cytoprotective effects were determined in human U937 cells incubated with oxidized LDL (OxLDL) using the 4-[3-(4-iodophenyl)-2-(4-nitrophenyl)-2H-5-tetrazolio]-1, 3-benzene disulfonate (WST-1) assay. The results demonstrated that the ethyl acetate extract showed cytoprotective activities. To identify the main cytoprotective components, a bioassay guided isolation of the ethyl acetate extract afforded b-sitosterol (1) and six flavonoids (2-7). Their chemical structures were established on the basis of spectroscopic evidence and comparison with literature data. Of these compounds, compound 6 was obtained from A. altilis for the first time. The cytoprotective effect offers good prospects for the medicinal applications of A. altilis.

Artocarpus↗

PubMed2006

Study on the technology of nitric oxide (NO) detection in vitro and in vivo.

To reveal the intracellular distribution of nitric oxide (NO) in single cell and to detect NO quantitatively in animal models, various methods are developed. A confocal microscope and 3D visualization technique were applied to visualize NO concentration in arbitrary directions and in different sections of cells. It was shown that NO distributions in cultured neurons of rat hipopocampus were not homogeneous. A kind of highly sensitive and selective NO electrode was utilized to measure the NO concentration in SD rat hippocampus, simultaneously with blood pressure and ECG recording. By the administration of N(G)-nitro-L-arginine methylester (L-NAME), the changes of NO level in the hippocampus in vivo were detected. It was shown that the NO level decreased greatly when NOS was inhibited by L-NAME with significant increase in blood pressure. The developed methods may be helpful to investigate the physiological mechanism of NO and its role in pathology.

Animals↗

PubMed2006

Investigation of beat-to-beat cardiovascular activity of rats by radio telemetry.

This paper was aimed to apply telemetry technology to investigate the cardiovascular activity of rats. A subminiature radio transducer was implanted in the body of rat to measure beat to beat blood pressure, ECG, body temperature, as well as the activity of rat continuously. Mathematic tools were developed to extract beat to beat cardiovascular parameters. Accordingly, spectral analysis of blood pressure variability and heart rate variability was performed to analyze cardiovascular activity in both normotensive and hypertensive rats. New indices were also established to assess the fluctuation of blood pressure of hypertensive rats and thus the effect of anti-hypertensive medication. The ratio of low frequency power to high frequency power in heart rate variability of normotensive rats was much lower than that of hypertensive rats. In hypertensive rats, the blood pressure variability demonstrated significant increase. Furthermore, the circadian rhythm of blood pressure and heart rate variability also altered in hypertensive rats. After the treatment, the blood pressure of hypertensive rats dropped significantly. Meanwhile, the developed indices, such as 24 h smoothness index were consistent with the behavior of blood pressure satisfactorily. The results suggest that the developed methods are powerful in studying cardiovascular system as well as evaluating the effects of antihypertensive medication objectively.

Animals↗

PubMed2006

[Analysis of rat 24h heart rate variability based on telemetry technology].

In this study ECG signal of unstrained rat was recorded by telemetry device, and heart rate variability (HRV) was analyzed in order to evaluate 24h autonomic nervous activity. The results demonstrated an obvious circadian rhythm in the autonomic nervous activity: sympathetic activity being dominant during wake phase, and parasympathetic activity, dominant during sleep phase. The ratio of the low frequency to high frequency components in HRV power spectrum (LF/HF) fluctuates with the change in the sleep stages. It is concluded that 24h HRV analyses may reveal plentiful information about the behavior of autonomic nervous system and thus facilitate the investigation of its regulating role in physiological and pathological processes.

Animals↗

PubMed2006

[The effects of embryonic bodies on differentiation of mouse embryonic stem cells to neuronal cells in vitro].

This study was directed at assessing the effects of embryonic bodies on differentiation of the embryonic stem cells. The embryonic bodies of different days gained by means of hanging, suspending and hung-suspended were processed by all-trans retinotic acids for 4 days. Then they were detected by immunocytochemistry methods and were measured to detect the fluorescence intensity changes of calcium after Glu stimulation. During this period, we observed the differentiation process and compared the differentiation ratio of embryonic stem cells processed by means of hanging, suspending for several days. It was found that the differentiation ratio of EBs obtained by suspending for 3 days, or by hanging for 3 days and suspending for 1 day, is relatively higher, which can help us find out the intrinsic differentiation mechanism of embryonic stem cells.

Animals↗

PubMed2005

Cell cycle synchronization of embryonic stem cells: effect of serum deprivation on the differentiation of embryonic bodies in vitro.

Research on stem-cell transplantation has indicated that the success of transplantation largely depends on synchronizing donor cells into the G0/G1 phase. In this study, we investigated the profile of embryonic stem (ES) cell synchronization and its effect on the formation of embryonic bodies (EBs) using cell culture with serum deprivation. The D3 cell line of ES cells was used, and parameters such as cell proliferation and activity, EB formation, and expression of stage-specific embryonic antigen-1 and Oct-4 were investigated. Results showed that the percentage of G0/G1 stage in serum deprivation culture is significantly higher than that in culture with serum supplementation. Synchronized ES cells can reenter the normal cell cycle successfully after serum supply. EBs formed from synchronized ES cells have higher totipotency capability to differentiate into functional neuronal cells than EBs formed from unsynchronized ES cells. Our study provides a method for ES treatment before cell transplantation that possibly helps to decrease the rate of cell death after transplantation.

Cell Culture Techniques↗

PubMed2005

The Neuroprotection of puerarin against cerebral ischemia is associated with the prevention of apoptosis in rats.

Previous work has shown that puerarin (Pur), extracted from the dried root of Pueraria lobata (Wild) Ohwi, increases cerebral blood flow in dogs and attenuates cerebral and spinal cord injury resulting from ischemia and reperfusion in rats and rabbits. The present study further demonstrates the neuroprotective effects of Pur on cerebral ischemic injury in rats and the mechanisms underlying the protective effects. Male Sprague-Dawley rats were subjected to middle cerebral artery occlusion (MCAo) for 50 min followed by reperfusion for 24 h. Pur (50, 100 mg/kg, i.p) was administered at the onset of MCAo. Twenty-four hours after reperfusion, neurological deficits were evaluated in Pur- and vehicle-treated rats. The infarct volume and edema ratios were assessed from stained brain slices. The results showed that Pur (100 mg/kg) markedly decreased the infarct volume by 34 % ( P < 0.01) in cerebral cortex and improved the neurological functions ( P < 0.05) after MCAo. Furthermore, flow cytometric analysis of annexin-V and PI labeling cells showed that the percentages of apoptosis and necrosis in the dorsolateral cortex were significantly reduced by 38.6 % and 28.5 % ( P < 0.01 and P < 0.05) following treatment with Pur (100 mg/kg) in MCAo rats. Caspase-3 activity, a biochemical marker of apoptosis, was significantly inhibited after treatment with Pur in the dorsolateral cortex. In agreement with this result, the expression of the X-chromosome-linked inhibitor of apoptosis protein (XIAP) was obviously up-regulated after administration of Pur (100 mg/kg), while caspase-3 gene was down-regulated in the dorsolateral cortex. These results suggest that the neuroprotection of puerarin against cerebral ischemia is associated with anti-apoptosis.

Animals↗

PubMed2005

Evaluation of antiviral activity of compounds isolated from Ranunculus sieboldii and Ranunculus sceleratus.

Nineteen compounds isolated from Ranunculus sieboldii and Ranunculus sceleratus were tested for inhibitory effects on hepatitis B virus (HBV) and Herpes simplex virus type-1 (HSV-1). The results showed that apigenin 4'- O- alpha-rhamnopyranoside, apigenin 7- O- beta-glucopyranosyl-4'- O- alpha-rhamnopyranoside, tricin 7- O- beta-glucopyranoside, tricin, and isoscopoletin possessed inhibitory activity against HBV replication. Protocatechuyl aldehyde exhibited an inhibiting activity on HSV-1 replication. It is therefore suggested that further investigations on these bioactive compounds might be needed to discover and develop new antiviral agents.

Antiviral Agents↗

PubMed2005

[Measurement of monoamine transmitters in the brains of ovariectomized mice using high performance liquid chromatography with fluorescence detection and gradient flow rate elution].

A method for the determination of norepinephrine (NE), dopamine (DA) and 5-hydroxytryptamine (5-HT) in brains of ovariectomized mice was established by using high performance liquid chromatograph with a fluorescence detector, a C18 column and a gradient flow rate delivered by a single pump. The mobile phase was a mixture of 0.1 mol/L KH2PO4 and CH3OH (9/1, v/v). Detection limits of the method were determined to be lower than 10 nmol/L, absolute recoveries were above 80% and the relative standard deviations (RSDs) of intra-day were all within 3.03%. The method has the advantages of high sensitivity and of simple sample preparation. Short analysis time and better separation of samples were also obtained.

Animals↗

PubMed2005

[Establishment of a system for measuring blood flow velocity of rat microvessel using dark background fluorescent image analysis method].

Autologous red blood cells (RBC) labeled with fluorescence were immitted into microvessel of SD rat and observed under microscope. The movement of each individual labeled RBC was recorded by microscope video camera system. The recorded videotape is replayed to sample dark background fluorescent images through frame grabber. Sampled frame images were separated into odd and even field sequence images. Then these sequence images were analyzed to get the flow rate. The error between the actual flow velocity value and the flow velocity value of fluorescent globules in the chamber measured under the same system was below 7%. The upper limit was 9.6 mm/s. There are no obvious differences (P > 0.05). This system has been applied in the research of rat microcirculatory disturbance, and the temporal flow rate change in microvessel was obtained.

Animals↗

PubMed2004

Nitric oxide imaging in neurons using confocal microscopy.

The instability and low concentration of nitric oxide (NO) in specimens make it difficult to be detected directly. In this chapter, a method for imaging nitric oxide using laser scanning confocal microscopy (LSCM) is presented. A cultured hippocampal neuron is dyed with DAF-2 and observed under a Zeiss LSM 510 laser scanning confocal microscope. A 488-nm laser power is applied as excitation and the emission light from the labeled nitric oxide in the neuron is detected. In this way, nitric oxide is imaged and its intracellular kinetic change is monitored. Furthermore, image processing and visualization techniques are employed to help analyze the image data.

Animals↗

PubMed2003

Inhibitory effect of jujuboside A on glutamate-mediated excitatory signal pathway in hippocampus.

Jujuboside A (JuA) is a main component of jujubogenin extracted from the seed of Ziziphus jujuba Mill var spinosa (Bunge) Hu ex H F Chou (Ziziphus), which is widely used in Chinese traditional medicine for the treatment of insomnia and anxiety. Previously, we reported the inhibitory effects of JuA on hippocampal formation in vivo and in vitro, the present study was carried out to examine the effects of JuA on glutamate (Glu)-mediated excitatory signal pathway in hippocampus. Microdialysis coupled with high-performance liquid chromatography (HPLC) was used to monitor the changes of Glu levels in the hippocampus induced by penicillin sodium, or a mixture of penicillin sodium and JuA. The results showed that penicillin increased the hippocampal Glu concentration (p < 0.01) and a high dose of JuA (0.1 g/L) significantly blocked penicillin-induced Glu release (p < 0.05). Moreover, the effect of JuA on intracellular Ca2+ changes after the stimulation by Glu was studied in cultured hippocampal neurons with confocal laser scanning microscope (CLSM). It was found that Glu (0.5 mM) induced an intracellular [Ca2+]i increase (p < 0.01), and JuA significantly inhibited the Glu-induced Ca2+ increase. The calmodulin (CaM) antagonist trifluoperazine (TFP) showed a similar inhibitory effect as JuA. These observations suggested that JuA has inhibitory effects on Glu-mediated excitatory signal pathway in hippocampus and probably acts through its anti-calmodulin action.

Animals↗

PubMed2002

The inhibitory effects of jujuboside A on rat hippocampus in vivo and in vitro.

Jujuboside A (JuA) is a glycoside extracted from the seed of Ziziphus jujuba Mill var. spinosa (Bunge) Hu ex H F Chou, a Chinese herbal medicine, which has long been known as a sedative-hypnotic drug. The present study used the method of intracerebroventricular (i.c.v.) JuA in vivo to detect the effect of JuA on paired-pulse responses of dentate gyrus granule cells in urethane-anaesthetized rats, and the method of hippocampal slice bathing in JuA in vitro to detect the effects of JuA on the responses of CA1 pyramidal cells. The results showed that JuA significantly decreased the slopes of excitatory postsynaptic potential (EPSP) and the amplitudes of population spike (PS) in the first responses of granule cells and significantly decreased EPSP and PS in the responses of CA1 pyramidal cells. The good quantitative correspondence between in vitro and in vivo results indicates that studies using hippocampal formation allow research on the inhibitory effects of JuA in the rat central nervous system (CNS). In conclusion, our study accessed the inhibitory effects of JuA on hippocampal formation in vivo and in vitro, which contributed to the further research on the mechanism of its effects on CNS.

Animals↗

PubMed2002

[Effects of sampling parameter variation on the complexity analysis of EEG].

The algorithmic complexity and the approximate entropy of EEG were calculated and analyzed with different data points, different sample frequencies and different sample time duration. The results showed that under fixed sample frequency, the longer the data was, the more stable the complexity values were. With fixed sample time duration or fixed data point, lower sample frequency would be better both for EEG distinguishing and for computing time saving.

Algorithms↗

PubMed2002

[Hypocholesterolemic effect of total isoflavones from Pueraria lobata in ovariectomized rats].

OBJECTIVE: To observe the effects of total isoflavones from Pueraria lobata (TIP) on lipid metabolism in estrogen deficient rat. METHODS: Female SD rats were bilaterally ovariectomized under anesthesia. TIP was administrated orally for 7 months. Serum lipids were determined at 1.5, 4.0 and 7.0 months, and liver lipids were detected at 7 months. RESULTS: Compared with non-ovariectomized rats, serum TC level and the ration of TC/HDL-C in ovariectomized rats were obviously increased while HLD-C was slightly induced and TG level were changeless. In TIP-treated groups, serum TC level and the ratios of TC/HDL-C were markedly lowered than those in OVX group, while HDL-C slightly increased. TG level were much reduced in 1.5 month and changeless in 4.0 and 7.0 month. Slightly increase of cholesterol and markedly induction of triglyceride tissue were observed in liver. CONCLUSION: TIP significantly decreased concentrations of serum TC and liver TG in OVX rats.

Animals↗