Biomedical subjects

Xiao-Ling Fang

Publications and source records attributed to Xiao-Ling Fang.

5 recordsLinked to original sources

PubMed2006

Difference in oral absorption of ginsenoside Rg1 between in vitro and in vivo models.

AIM: To clarify the cause of poor oral absorption of ginsenoside Rg1 (Rg1), the active ingredient in Panax notoginseng saponins (PNS) used for treating hemorrhage. METHODS: Caco-2 cell monolayers were used as an in vitro model to study the transport mechanism of Rg1 across the intestinal mucosa. Moreover, the serum concentration-time profiles after peroral (po), intraduodenal (id), portal venous (pv) and tail venous (iv) administration of Rg1 in rats were compared to evaluate the first-pass effects in the stomach, intestine, and liver. RESULTS: Uptake of Rg1 by Caco-2 cell monolayers was temperature-dependent, but was not influenced by cyclosporin A. The change in the apical pH produced no obvious effect on the uptake of Rg1. The uptake and transport of Rg1 was non-saturable; whereas the flux from the apical compartment to the basolateral compartment (A-B) increased in a linear manner with the increase in concentration, indicating passive transport. An apparent permeability coefficient of (2.59+/-0.17)*10(-7) cm/s (C0=1 mg/mL) predicted incomplete absorption. A significant difference was observed between the po (F(po) was 3.29% at a dose of 1500 mg/kg), id (F(id) was 6.60% at a dose of 1200 mg/kg) and pv (F(pv) was 50.56%) administration methods, and the barrier function of the intestine was more significant than those of the stomach and liver in the absorption process. CONCLUSION: Elimination in the stomach, large intestine and liver contributed to the low oral bioavailability of Rg1, but low membrane permeability might be a more important factor in determining the extent of absorption.

Administration, Oral↗

PubMed2006

Pharmacokinetics and biodistribution of polymeric micelles of paclitaxel with Pluronic P123.

AIM: To investigate the preparation, in vitro release, in vivo pharmacokinetics and tissue distribution of a novel polymeric micellar formulation of paclitaxel (PTX) with Pluronic P123. METHODS: The polymeric micelles of paclitaxel with Pluronic P123 were prepared by a solid dispersion method. The characteristics of micelles including particle size distribution, morphology and in vitro release of PTX from micelles were carried out. PTX-loaded micellar solutions were administered through the tail vein to healthy Sprague-Dawley rats and Kunming strain mice to assess the pharmacokinetics and tissue distribution of PTX, respectively. Taxol, the commercially available intravenous formulation of PTX, was also administered as control. RESULTS: By using a dynamic light scattering sizer and a transmission electron microscopy, it was shown that the PTX-loaded micelles had a mean size of approximately 25 nm with narrow size distribution and a spherical shape. PTX was continuously released from Pluronic P123 micelles in release medium containing 1 mol/L sodium salicylate for 24 h at 37 centigrade degree. In the pharmacokinetic assessment, t(1/2beta) and AUC of micelle formulation were 2.3 and 2.9-fold higher than that of Taxol injection. And the PTX-loaded micelles increased the uptake of PTX in the plasma, ovary and uterus, lung, and kidney, but decreased uptake in the liver and brain in the biodistribution study. CONCLUSION: Polymeric micelles using Pluronic P123 can effectively solubilize PTX, prolong blood circulation time and modify the biodistribution of PTX.

Animals↗

PubMed2006

[Effect of self-microemulsifying system on cell tight junctions].

AIM: To study the effect of negatively charged and positively charged self-microemulsifying systems (SMES) on the cellular tight junction complex was to be investigated at molecular cell level. METHODS: Human intestinal epithelial Caco-2 cell model was established. Effect of formulations on the transepithelial electrical resistance (TEER) and permeability of the paracellular transport marker mannitol were measured to evaluate the cell integrity. Changes in subcellular localization of the tight junction protein zona occludens 1 (ZO-1) and cytoskeleton protein actin by immunofluorescence were also assessed after treatment of two SMESs in different dilutions. RESULTS: The TEER of cell monolayers was not markedly affected by negatively charged SMES in different dilutions. The positively charged SMES could significantly decrease the TEER (P < 0.05) in three dilutions. The full recovery of TEER was found after the treatment of lower dilution for 2 h, then cultured for 48 h, while the recovery of TEER was 81.3% of control in 1 : 50 dilution. Two SMESs could enhance the apparent permeability coefficient of mannitol (2.9 - 64.6 folds), which depended on the dilution times. The immunofluorescent results indicated that the distribution of ZO-1 and actin were discrete in cell membrane after the treatment of formulation. Since the positively charged microemulsion could bind to the epithelial cell membrane by electrostatic interaction, the actin of the cells undergone some kind of stress stimulated by the higher concentration of microemulsion was more markedly affected than the negatively charged SMES. Effect of formulations on ZO-1 and actin relied on the dilution. CONCLUSION: SMES is able to enhance the paracellular transport marker mannitol. The mechanism of opening of tight junctions by SMES might be the change of distribution of ZO-1 and actin.

Actins↗

PubMed2006

[Mechanism of oral absorption of panaxnotoginseng saponins].

AIM: To study the mechanism of absorption after oral administration of panaxnotoginseng saponins (PNS). METHODS: Caco-2 cells and rat models were applied to evaluate the degradation of both ginsenoside Rb1 (Rb1) and ginsenoside Rg1 (Rg1) in PNS in gastrointestinal lumen, and the transport mechanism of PNS across the intestinal mucosa, and the barrier function of stomach, intestine and liver involved in absorption process. RESULTS: Rb1 and Rg1 proved to be readily eliminated in stomach, but stable in relatively neutral circumstance. Both Rb1 and Rg1 in PNS, especially for Rb1, degraded significantly in the contents of large intestine. However, both of them kept mainly intact in the contents of small intestine. Uptake of both Rb1 and Rg1 by Caco-2 cell monolayer was inhibited at low temperature, but not by cyclosporine A, and the change in the apical pH showed no pronounced effect. Uptake and transport were non-saturable and increased linearly with increasing of concentrations of Rb1 and Rg1 over the range of concentration tested, which indicated a passive transport. There was no significant difference of absorption characteristic between monomer (Rb1 and Rg1) and mixture (PNS). Uptake amount of Rg1 [(1.07 +/- 0.16) microg x mg(-1) (protein)] (C0 = 1 mg x mL(-1)) in Caco-2 cells was a little higher than that of Rb1 [(0.77 +/- 0.03) microg x mg(-1) (protein)] (C0 = 1 mg x mL(-1)). Meanwhile, apparent permeability coefficient of (5.9 +/- 1.0) x 10(-8) cm x s(-1) (C0 = 1 mg x mL(-1)) for Rb1 and (2.59 +/- 0.17) x 10(-7) cm x s(-1) (C0 = 1 mg x mL(-1)) for Rg1 from apical compartment to basolateral compartment predicted an incompletely absorption. Transports of both Rb1 and Rg1 were not influenced by cyclosporine A. The investigation on the pharmacokinetic behavior of Rb1 and Rg1 after different routes of administration to rats showed that the absolute bioavailability after peroral (po), intraduodenal (id), and portal venous (pv) administration is 0.71% , 2.75% and 65.77% respectively for Rb1, and 3.29%, 6.60% and 50.56% respectively for Rg1. CONCLUSION: Transport across Caco-2 cell monolayer for PNS (include Rb1 and Rg1) is a simple passive diffusion process. No efflux transporters in Caco-2 cells and other components in PNS showed effects on it. The elimination in stomach, large intestine and liver contributed to the low bioavailability of PNS, but the low membrane permeability might be a more important factor dominating the extent of absorption.

Administration, Oral↗

PubMed2005

[Effect of progesterone on the secretion of matrix metalloproteinase-2 and matrix metalloproteinase-9 in human ectopic endometrial stromal cells].

OBJECTIVE: To determine the effect of progesterone on the secretion of matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9) in ectopic endometrial stromal cells. METHODS: Ectopic endometrial stromal cells were obtained from 17 patients with endometriosis. Endometrial stromal cells were obtained from 12 patients with endometriosis and 14 cases of controls. Ectopic endometrial stromal cells of 15 cases were treated with progesterone. Culture supernatants of these stromal cells were analyzed for MMP-2 and MMP-9 by zymography. RESULTS: Endometriotic stromal cells released significantly higher levels of MMP-2 and MMP-9 than endometrial stromal cells from women with and without endometriosis. Progesterone at 10(-9) mol/L caused endometriotic stromal cells a significant reduction MMP-2 and MMP-9 levels. When progesterone concentration was increased from 10(-9) mol/L to 10(-7) mol/L, the release of MMP-9 was almost completely inhibited, wherease that of MMP-2 was not completely inhibited. CONCLUSION: Progesterone may inhibit the secretion of MMP-2 and MMP-9 in ectopic endometrial stromal cells, especially MMP-9.

Adult↗