Biomedical subjects

Zonghua Wang

Publications and source records attributed to Zonghua Wang.

6 recordsLinked to original sources

PubMed2005

[Determination of lactone components in chuanxiong by reversed-phase high performance liquid chromatography].

A reversed-phase high performance liquid chromatographic method was developed for the simultaneous determination of four main lactone components including senkyunolide-H, senkyunolide-I, sedanenolide and Z-ligustilide in Chuanxiong, a Chinese herbal medicine. The samples were pretreated using ultrasonic extraction, and 80% ethanol was used as extractant in the experiment. The chromatographic analysis was carried out using an XDB-C8 column and the mobile phase consisted of methanol-1% (volume fraction) acetic acid water (55:45-->100:0, v/v, in 15 min). The flow rate was 0. 8 mL/min. A diode array detector was used to detect the compositions and 280 nm was chosen as the detection wavelength. The whole process could be performed within 15 min. The operating curves were found to be linear over the ranges of 0.4 - 2.2 mg/L (r=0. 9992), 0.4 -2.2 mg/L (r=0.9979), 2.6 -7.8 mg/L (r=0. 9992) and 4.8 14.3 mg/L (r = 0.9998) and the detection limits (S/N = 3) were 0.024, 0.027, 0.018 and 0.011 microg for senkyunolide-H, senkyunolide-I, sedanenolide and Z-ligustilide, respectively. The recoveries of the four lactone components were found in the range of 96% - 108%. The rapid and accurate method has been successfully applied to the simultaneous determination of the four lactone components in Chuanxiong.

4-Butyrolactone↗

PubMed2004

ROP/RAC GTPase: an old new master regulator for plant signaling.

The ROP family of small GTPases has emerged as a versatile and pivotal regulator in plant signal transduction. Recent studies have implicated ROP signaling in diverse processes ranging from cytoskeletal organization to hormone and stress responses. Acting as a switch early in signaling cascades, ROPs are also capable of orchestrating several downstream pathways to amplify a specific signal.

Actins↗

PubMed2003

Ligand-independent activation of estrogen receptor alpha by XBP-1.

The estrogen receptor (ER) is a member of a large superfamily of nuclear receptors that regulates the transcription of estrogen-responsive genes. Several recent studies have demonstrated that XBP-1 mRNA expression is associated with ERalpha status in breast tumors. However, the role of XBP-1 in ERalpha signaling remains to be elucidated. More recently, two forms of XBP-1 were identified due to its unconventional splicing. We refer to the spliced and unspliced forms of XBP-1 as XBP-1S and XBP-1U, respectively. Here, we report that XBP-1S and XBP-1U enhanced ERalpha-dependent transcriptional activity in a ligand-independent manner. XBP-1S had stronger activity than XBP-1U. The maximal effects of XBP-1S and XBP-1U on ERalpha transactivation were observed when they were co-expressed with full-length ERalpha. SRC-1, the p160 steroid receptor coactivator family member, synergized with XBP-1S or XBP-1U to potentiate ERalpha activity. XBP-1S and XBP-1U bound to the ERalpha both in vitro and in vivo in a ligand-independent fashion. XBP-1S and XBP-1U interacted with the ERalpha region containing the DNA-binding domain. The ERalpha-interacting regions on XBP-1S and XBP-1U have been mapped to two regions, including the N-terminal basic region leucine zipper domain (bZIP) and the C-terminal activation domain. The bZIP-deleted mutants of XBP-1S and XBP-1U completely abolished ERalpha transactivation by XBP-1S and XBP-1U. These findings suggest that XBP-1S and XBP-1U may directly modulate ERalpha signaling in both the absence and presence of estrogen and, therefore, may play important roles in the proliferation of normal and malignant estrogen-regulated tissues.

Blotting, Western↗

PubMed2003

Carbon nanotubes as separation carrier in capillary electrophoresis.

The utility and versatility of carboxylic single-walled carbon nanotubes (c-SWNT) in capillary electrophoresis (CE) is demonstrated, using as model solutes homologues and structural isomers. In the case of homologues of caffeine and theobromine, distinct changes in the electrophoretic parameters occur at a critical concentration of c-SWNT in the run buffer. It is suggested that the c-SWNT of a definite concentration could form a network in the run buffer as a pseudostationary phase on the basis of the unique tubule structure, providing a different separation from sodium dodecyl sulfate (SDS) micelles. In the case of structural isomers of catechol and hydroquinone, differing from the homologues, it is mainly attributable to the functional groups on the c-SWNT that have an effect on the electrophoretic behaviors by forming intermolecular hydrogen bonding with analytes. Furthermore, aggregated c-SWNT serve as anticonvective media and minimize solute diffusion contributing to zone broadening. The presence of charged c-SWNT suppressed the electrodiffusion and decreased the adsorption between capillary wall and solutes, which led to better peak shapes of isomers.

Caffeine↗

PubMed2002

Carbon nanotube-modified electrodes for the simultaneous determination of dopamine and ascorbic acid.

The voltammetric separation of dopamine and ascorbic acid was studied with cyclic voltammetry at two kinds of carbon nanotube-modified electrodes (coated and intercalated). The anodic peak difference reached 270 mV under the present conditions. The separation mechanism and effect factors were carefully studied. Using various types of surfactants as coating dispersants of carbon nanotubes, it was demonstrated that the charge nature of the surfactants had a strong effect on the electrochemical behavior of dopamine and ascorbic acid. When the oxidation solution of carbon nanotubes was changed from the most commonly used mixed concentrated nitric acid and sulfuric acid (1 + 3 v/v) to dilute nitric acid and to hydrochloric acid, the anodic peak separation value of dopamine and ascorbic acid increased significantly, and it was shown that carboxylic acid groups attached to the carbon nanotubes were an adverse factor for the discrimination of DA from AA. These results indicated that the resolution of DA and AA was mainly attributable to the stereo porous interfacial layer formed from aggregated pores and inner cavities of the carbon nanotubes. The modified electrodes exhibited an attractive ability to measure DA and AA simultaneously and showed good stability and reproducibility.

Ascorbic Acid↗

PubMed2002

A selective voltammetric method for uric acid detection at beta-cyclodextrin modified electrode incorporating carbon nanotubes.

A beta-cyclodextrin-coated electrode incorporating carbon nanotubes was constructed and applied to the detection of uric acid in the presence of high concentration of ascorbic acid. The major obstacle of the overlapped oxidation potential of ascorbic acid was overcome owing to the distinct ability of the carbon nanotubes-modified electrode to yield a large anodic peak difference ca. 400 mV. The sensitive detection of uric acid has been further improved by the formation of a supramolecular complex between beta-cyclodextrin and uric acid. A linear calibration curve was obtained for 5 x 10(-7) to 5 x 10(-5) M in 0.2 M HAc-NaAc buffer (pH 4.5) with correlation coefficient of 0.998 and detection limit of 0.2 microM. The practical analytical application was illustrated by a selective measurement of uric acid in human urine without any preliminary treatment.

Ascorbic Acid↗