Biomedical subjects

Li-Qun Wang

Publications and source records attributed to Li-Qun Wang.

9 recordsLinked to original sources

PubMed2006

Micellization phenomena of amphiphilic block copolymers based on methoxy poly(ethylene glycol) and either crystalline or amorphous poly(caprolactone-b-lactide).

This study focuses on the aggregation behavior of the biodegradable amphiphilic block copolymers based on methoxy poly(ethylene glycol) (mPEG) as a hydrophilic block and either crystalline poly(caprolactone-b-l-lactide) (P(CL-LLA)) or amorphous poly(caprolactone-b-D,L-lactide) (P(CL-DLLA)) as a hydrophobic block. These block copolymers have a strong tendency to form micelles in aqueous medium, with very low critical micelle concentrations (CMCs). The CMC of P(CL-LLA)-b-mPEG is higher than that of P(CL-DLLA)-b-mPEG when the mPEG block has the same molecular weight. Furthermore, the partition equilibrium coefficient (K(v)) of pyrene in the micellar solution of P(CL-LLA)-b-mPEG copolymer was lower than that of P(CL-DLLA)-b-mPEG copolymer when the mPEG block was the same length. These differences were believed to be related to the physical state of the core-forming blocks, i.e., the crystalline P(CL-LLA) block and the amorphous P(CL-DLLA) block. The TEM images showed that micelles formed by P(CL-LLA)-b-mPEG assembled in a cylindrical morphology, whereas those formed by P(CL-DLLA)-b-mPEG took a classical spherical shape. In addition, with differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD) analyses, it is believed that the crystallization tendency of the core-forming blocks is the main factor governing the morphology of micelles in water. A possible mechanism for the cylindrical assembly morphology was discussed.

Biocompatible Materials↗

PubMed2005

Long-range EEG phase synchronization during an arithmetic task indexes a coherent cortical network simultaneously measured by fMRI.

An open question lies in whether or not distributed activities in the distant brain regions are integrated into a coherent ensemble for cognitive information processing. Long-range phase synchronization is often observed by scalp EEG measurements during cognitive tasks and is considered to provide a possible neural principle for the functional integration of distributed neural activities. Synchronization could be reflected at the neuron firing level or at the local field potential and could appear in the scalp EEG under certain conditions on neural spatial and temporal coherence. To examine if phase synchronization is concerned with the integration of distant regions, we proposed a method to extract brain activities associated with task-dependent phase synchronization by combining simultaneous fMRI and EEG. By applying this method in a mental arithmetic task, we found a dominant task-dependent increase of phase synchronization around 14 Hz (in beta frequency) across bilateral parietal sites that were associated with both negative and positive BOLD responses. Functional connectivity analyses of these regions demonstrated that an increase in hemispheric beta synchronization was associated with a linking between the cross-hemispheric regions (left angular gyrus and right superior parietal gyrus) and also among the anterior-posterior regions (right dorsolateral prefrontal cortex, putamen, and right superior temporal gyrus). These findings indicate that the positive BOLD regions (dorsolateral prefrontal cortex and superior parietal lobule) are linked with other negative BOLD regions. We also discussed the possible importance of beta synchronization in the formation of a working memory network.

Adult↗

PubMed2004

A long-range cortical network emerging with theta oscillation in a mental task.

Human scalp EEG has demonstrated that global coherence among distant areas increases during cognitive tasks, suggesting that oscillating neural activities work to generate global neuronal assemblies for cognitive functions. The theta oscillation in a frequency range of 4-8 Hz with large amplitudes which emerges during mental tasks around the frontal midline region is called fm theta. If theta oscillation concerns the global neuronal assemblies, fm theta should be associated with regional activities that depend on task conditions. In the present study, we examine the EEG-related brain activities by developing simultaneous EEG and fMRI during a mental calculation task. EEG-related negative BOLD was dominant over anterior medial regions, suggesting a major contribution of negative BOLD to fm theta. Negative and positive BOLD were found over distant regions. Functional connectivity analyses revealed that the connectivity varied remarkably according to mental conditions. In the rest condition, the connectivity was localized, whereas in the task condition, a long-range coherent network was formed by the anterior midline, posterior cingulate and right middle temporal cortices with linking between the right middle temporal and left lateral cortices during numerical processing. Further EEG analyses indicate that the long-range coherent network executing cognitive functions is coordinated in the time window of theta oscillations.

Action Potentials↗

PubMed2004

Cloning and characterization of a novel human RNA binding protein gene PNO1.

Present work reported the cloning and characterization of a human novel RNA binding gene Partner of NOB1 (PNO1), with a length of 1637bp and a putative open reading frame of 759 bp, isolated from human kidney. It is composed of seven exons and is localized on chromosome 2p14. Western blot showed that the molecular weight of PNO1 is about 35kDa. RT-PCR results in 16 human tissues indicated that PNO1 is expressed mainly in liver, lung, spleen and kidney, slightly in thymus, testis, ovary, respectively, but not in heart, brain, skeletal muscle, placenta, pancreas, prostate, small intestine, colon and peripheral blood leukocytes. GFP fusion expression in mammalian cells exhibited its localization in the nucleus, especially in nucleoli. Subcellular localization of thirteen GFP fusion PNO1 deletion proteins showed that the region of 92-230 aa is solely responsible for its nucleolar retention, and KH domain alone is not sufficient for nucleolar retention. The PNO1 family shows significant conservation in both eukaryotes and prokaryotes.

Amino Acid Sequence↗

PubMed2004

[Quality assessment for Coptis chinensis planted with ecological techniques].

OBJECTIVE: To evaluate the quality difference between Coptis chinensis planted with ecological techniques and shelf planted Coptis chinensis. METHODS: Ultraviolet-visible spectrophotometry, alcohol extract mensuration, moisture mensuration, and ash mensuration were used to determine the contents of total alkaloids, alcohol extract, water, and total ash of Coptis chinensis, which were planted in shelf, Rhus chinensis wood, M mulbery wood, corn wood, Magnolia officinalis wood, fruiter wood, shading net, and firry wood, respectively. RESULTS: The contents of total alkaloids and alcohol extract of Coptis chinensis Table planted with ecological techniques were higher than those of Coptis chinensis planted in shelf. The contents of water and total ash were less than 12% and 5%, respectively, which met the provisions of the pharmacopoeia. CONCLUSION: The quality of Coptis chinensis planted with ecological techniques is similar to that of Coptis chinensis planted in shelf. These ecological techniques for Coptis chinensis have become mature and practical.

Agriculture↗

PubMed2004

[Analysis and assessment of Coptis chinensis for different parts, ages, and heights using Fourier transform infrared spectroscopy].

OBJECTIVE: To study the infrared (IR) fingerprint spectra of Coptis chinensis for different parts, ages, and heights, and to analyze the integrate rules about the content of berberine component in Coptis chinensis for different parts, ages, and heights. METHOD: The Fourier transform infrared (FTIR) spectroscopy was applied to detect the infrared spectra of Coptis chinensis samples rapidly and non-separately. RESULTS: The IR spectra of the root, leafstalk, and fibre of Coptis chinesis have their unique features. The content of berberine component in Coptis chinensis was different for different parts and the sequence: root > leafstalk > fibre. When Coptis chinensis grows, the content of berberine component in leafstalk also increases. The content of berberine component in leafstalk which planting in 1 200 m was less than that in 1 300, 1 400, and 1 500 m. The ages and heights provide no obvious influences on the content of berberine in the root of Coptis chinensis. CONCLUSION: Using FTIR spectroscopy, the quality of Coptis chinensis can be controlled, which provides a useful method for the standardized planting of Coptis chinensis.

Altitude↗

PubMed2004

[Analysis of contents of berberine in Coptis chinensis of Lichuan].

OBJECTIVE: To determine the contents of berberine in Coptis chinensis of Lichuan and establish its best cultivation scheme. METHOD: We used high performance liquid chromatography (HPLC) to measure the contents of berberine at different altitude, growth age, and leaves. RESULTS: Analytic data showed that the growth age and firry woods shading did not affect the contents of berberine in rhizome of Coptis chinensis. Low altitude was more suitable for Coptis chinensis to synthesize berberine. The contents of berberine in rhizome of Coptis chinensis with floral leaf were higher than those with lusterless and lustrous leaves, but no significant difference. CONCLUSION: The synthesis of berberine is closely correlated with shading conditions. It is recommended that the shading ratio should be reduced or the sheds removed in the middle growth age (2-3 years), and then the herb should be reshaped at the last year to enhance the synthesis of berberine, so as to obtain high-quality Coptis chinensis in the harvest.

Altitude↗

PubMed2004

[Research development of Coptis chinensis].

To summarize the research and application of ecological planting technique for Coptis chinensis, and describe the recent development of its chemical components, pharmacological effects and clinical applications.

Animals↗

PubMed2003

[Induced activity of nitrate reductase by nitrate and cloning of nitrate reductase gene].

Excessive nitrate accumulated in plants affects vegetable quality severely and excessive nitrate ingestion would do harm to human health. Assimilatory NADH: nitrate reductase (NR, EC 1.6.6.1), a complex Mo-pterin-, cytochrome b(557)- and FAD-containing protein, catalyzes the regulated and rate-limiting step in the utilization of inorganic nitrogen by higher plants. Enhancing the activity of NR is conducive to reduce the concentration of nitrate in plants. The experiments were conducted to investigate the activity of nitrate reductase in different plant tissues and the relationship between external inducing solution concentration and NR activity (NRA) in plant leaves. Six plant seedlings growing in solution culture were deprived of an external nitrogen (N) supply for 2 weeks. On selected days, three of six plant seedlings were exposed to 50mmol/L NO3- for 0, 2, 5, 8, 11h, and four of the six plant seedlings were exposed to 0, 10, 30, 50mmol/L NO3- for 2h. The NRA was determined in vivo at 538nm using spectrophotometer. The results showed that NRA increased when those plant seedlings were induced by nitrate solution. The change trends of NRA in roots and in leaves of cole, pea and tomato were different during treating time. The NRA in cole leaves was higher than that in its root and in other two plants and increased along with inducing time, but the NRA in bea and tomato was highest when the treating time was 8h and 2h, respectively. The highest NRA in leaves of three kinds of Chinese cabbages and tomato was induced by different concentrations of KNO3 solution. In tomato leaves, the highest NRA was induced by 10 - 30mmol/L KNO3 solution. In three Chinese cabbages, Brassica chinensis L. cv. AJH, XBC and KR-605, the highest NRA was induced by 10, 30, 10mmol/L KNO3 solution, respectively. The results indicated that the response manners of NRA in plants to external nitrate solutions were different. According to these results, the level of NR mRNA in plants could be enhanced by nitrate inducement. The total RNA was isolated from tomato leaves and root which induced by 30mmol/L KNO3 solution for 2h, and NR cDNA was obtained by RT-PCR using the specific primers. The fragments of PCR products were cloned and sequenced. There are 2736 base pairs in the whole cDNA fragment. The deduced protein sequence contains 911 amino acids. The NR gene can be fused to the CaMV 35S promoter, then introduced to higher plants, such as vegetables. It is hoped to decrease drastically the nitrate content of the transgenic plants.

Brassica↗