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Qiang Fan

Publications and source records attributed to Qiang Fan.

5 recordsLinked to original sources
PubMed2006

Effect of substrate on surface-enhanced Raman scattering of molecules adsorbed on immobilized silver nanoparticles.

Silver nanoparticles were assembled on polyvinylpyridine (PVP) derivatized glass slides. Charge transfer between the adsorbed 4-aminothiophenol (PATP) and the immobilized silver nanoparticles was studied by surface-enhanced Raman spectroscopy with 1064 nm excitation, and compared with that of the silver nanoparticles in the colloid. It was demonstrated that the positive charges of the PVP layer could alter the charge distribution in the immobilized nanoparticles and induce the formation of the dipole in the nanoparticles, leading to less charge transfer from the metal to the adsorbed molecules. The coadsorption of chloride ions on the surface of the immobilized silver nanoparticles resulted in the redistribution of the charges in the nanoparticles and, in turn, altered the charge transfer between the adsorbed PATP molecules and the silver nanoparticles.

Journal Article↗
PubMed2006

[Study on the method of rapid quality control of aqueous solution of flos lonicerae japonicae extraction in the preparation of qingkailing injection].

To establish a rapid and accurate on-line quality control method for aqueous solution of Flos Lonicerae Japonicae extraction (ASFLJE) in the preparation of Qingkailing injection, the wavelength of UV original spectrum and its first derivative spectrum of ASFLJE were scanned. The most suitable spectrum type and wavelength correlated with the chlorogenic acid content in ASFLJE determined by RP-HPLC were chosen to build a regress model. The UV equation for predicting chlorogenic acid content in ASFLJE was established. Other 10 batches of ASFLJE were used for testing the on-line prediction results by comparison of the values of chlorogenic acid content determined by HPLC and predicting equation respectively. The most suitable wavelengths correlated with chlorogenic acid content were 294 nm (r = 0.991 9, n = 28) in the original UV spectrum and 316 nm (r = 0.995 9, n = 28) in the first derivative spectrum respectively. The predicting equation of chlorogenic acid content was: c(mg x mL(-1)) = 506. 254 3 x A316 nm + 0.177 1 (r = 0.995 9, n = 28). This predicting equation is credible and accurate, as tested by HPLC method (r = 0.991 5, n = 10). The prediction results of chlorogenic acid content were: the chlorogenic acid content in probable 90 percent ASFLJE was: 0.4-4.0(mg x mL(-1)). This method is rapid, simple and accurate, and can be used for the on-line quality control of ASFLJE in Qingkailing injection preparation.

Chlorogenic Acid↗
PubMed2004

Implication of delayed TNF-alpha exposure on dendritic cell maturation and expansion from cryopreserved cord blood CD34+ hematopoietic progenitors.

Most currently used systems for dendritic cell (DC) production from progenitors entail tumor necrosis factor alpha (TNF-alpha) at the onset of cell culture, based on the notion that TNF-alpha might be required in the early stages of DC development. To optimize conditions for DC expansion from cryopreserved cord blood (CB) CD34+ hematopoietic progenitors, we took a dynamic approach to define the timing of TNF-alpha exposure to the culture. We cultured cord blood CD34+ cells in RPMI-1640 with 10% human AB plasma, stem cell factor (days 1-6), granulocyte-macrophage colony-stimulating factor (days 1-18), interleukin-4 (days 6-18) and varying schedules of TNF-alpha (0-144 h after thawing). Expression of the DC-associated markers, including CD83/CD1a, HLA DR/CD86/CD80, CD14/CD40, was monitored every 3 days. Our data demonstrate that delayed TNF-alpha exposure by 48-72 h after thawing gave rise to two- to three-fold increase in the yield of CD83+ DCs that were highly active in stimulating allogeneic T-cell proliferation compared to immediate TNF-alpha exposure. Thus, the immediate exposure of cryopreserved cord blood CD34+ cells to TNF-alpha, potentially compromising DC expansion, should be avoided. This finding should be of significant consideration when using cryopreserved CD34+ progenitor cells as a source of immunologically competent DCs in a clinical setting.

Antigens, CD34↗
PubMed2003

Cyclooxygenase 2 and intermittent hypoxia-induced spatial deficits in the rat.

Intermittent hypoxia (IH) during sleep, a critical feature of sleep apnea, induces significant neurobehavioral deficits in the rat. Cyclooxygenase (COX)-2 is induced during stressful conditions such as cerebral ischemia and could play an important role in IH-induced learning deficits. We therefore examined COX-1 and COX-2 genes and COX-2 protein expression and activity (prostaglandin E2 [PGE2] tissue concentration) in cortical regions of rat brain after exposure to either IH (10% O2 alternating with 21% O2 every 90 seconds) or sustained hypoxia (10% O2). In addition, the effect of selective COX-2 inhibition with NS-398 on IH-induced neurobehavioral deficits was assessed. IH was associated with increased COX-2 protein and gene expression from Day 1 to Day 14 of exposure. No changes were found in COX-1 gene expression after exposure to hypoxia. IH-induced COX-2 upregulation was associated with increased PGE2 tissue levels, neuronal apoptosis, and neurobehavioral deficits. Administration of NS-398 abolished IH-induced apoptosis and PGE2 increases without modifying COX-2 mRNA expression. Furthermore, NS-398 treatment attenuated IH-induced deficits in the acquisition and retention of a spatial task in the water maze. We conclude that IH induces upregulation and activation of COX-2 in rat cortex and that COX-2 may play a role in IH-mediated neurobehavioral deficits.

Analysis of Variance↗