Enhanced oral bioavailability and anti-tumour effect of paclitaxel by 20(s)-ginsenoside Rg3 in vivo.

The purpose of this study was to investigate the effect of paclitaxel in combination with 20(s)-ginsenoside Rg3 on its anti-tumour effect in nude mice. In the Caco-2 transport assay, the apparent permeability from the apical side to the basal side (P(app)) (A-B) and P(app) (B-A) of paclitaxel were measured when co-incubated with different concentrations of 20(s)-ginsenoside Rg3. The results indicated that the penetration of paclitaxel through the Caco-2 monolayer from the apical side to the basal side was facilitated by 20(s)-ginsenoside Rg3 in a concentration-dependent manner. Meanwhile, 20(s)-ginsenoside Rg3 inhibited P-glycoprotein (P-gp), and the maximum inhibition was achieved at 80 µM (p < 0.05). The pharmacokinetic parameters of paclitaxel after oral co-administration of paclitaxel (40 mg/kg) with various doses of 20(s)-ginsenoside Rg3 in rats were investigated by an in vivo pharmacokinetic experiment. The results showed that the AUC of paclitaxel co-administered with 20(s)-ginsenoside Rg3 was significantly higher (p < 0.001 at 10 mg/kg) compared with the control. The relative bioavailability (RB) % of paclitaxel with 20(s)-ginsenoside Rg3 was 3.4-fold (10 mg/kg) higher than that of the control. The effect of paclitaxel orally co-administered with 20(s)-ginsenoside Rg3 against human tumour MCF-7 xenografts in nude mice was also evaluated. Paclitaxel (20 mg/kg) co-administered with 20(s)-ginsenoside Rg3 (10 mg/kg) exhibited an effective anti-tumour activity with the relative tumor growth rate (T/C) values of 39.36% (p <0.05). The results showed that 20(s)-ginsenoside Rg3 enhanced the oral bioavailability of paclitaxel in rats and improved the anti-tumour activity in nude mice, indicating that oral co-administration of paclitaxel with 20(s)-ginsenoside Rg3 could provide an effective strategy in addition to the established i.v. route.

[Construction of a gastric cancer related gene GCRG213-specific siRNA expression vector and its effect on gastric cancer cells in vitro].

OBJECTIVE: To investigate the effect of gene GCRG213 siRNA transfection into gastric cancer cell line MKN45 cells. METHODS: Two pairs of DNA sequences containing small hairpin structure to GCRG213 were designed and synthesized. The complement form was obtained by annealing and inserted into RNAi expression vector IMG-800. They are IMG-800-1 and IMG-800-2 correspondingly. The recombinant plasmid IMG-800-1, IMG-800-2 and the vector IMG-800 were separately transfected into MKN45 cells conducted by lipofectamine 2000. After G418 selecting, the cells were transfected steadily. Expression of GCRG213 was detected by semi-quantitative RT-PCR and Western Blot. The growth graph of six steady transfected cell cultures was protracted by cell counting. FACS was used to detect the cell cycle, and Annexin V FITC/PI double labeling were used to detect the effects on cell apoptosis in the above-mentioned cells. The clone formation rate in plate and in nude mice was tested to investigate the tumorigenic characteristics of the six steadily transfected cells in vitro and vivo. RESULTS: Through sequencing, two pairs of DNA sequences containing small hairpin structure to GCRG213 were proved to be successfully cloned into siRNA expression vector IMG-800, correspondingly called IMG-800-1 and IMG-800-2. The recombinant plasmid IMG-800-1, IMG-800-2 and vector IMG-800 were transfected separately into MKN45 cells conducted by lipofectamine 2000. After G418 selecting, the cells were transfected steadily. Transfecting the siRNA vector (IMG-800-1, IMG-800-2 ) into the MKN45 cells significantly decreased the expression of GCRG213, at both mRNA and protein levels. The growth graph showed that the growth of IMG-800-1 and IMG-800-2 transfected cells were slower than that of vector transfected cells. The proportion of cells in G2/M and/or S phase decreased in the cells transfected with IMG-800-1 and IMG-800-2 and cell apoptosis increased. The average clone formation rate in vitro decreased in the cells transfected with IMG-800-1 and IMG-800-2, compared with those transfected with vector. In vivo, the time of tumor formation of IMG-800-1 and IMG - 800-2 transducted cells in nude mice was prolonged and the tumor size was smaller. CONCLUSION: GCRG213 SiRNA transfection may induce inhibition of growth and proliferation of tumor cells, promote cell apoptosis, and inhibit the tumorigenicity in vitro and vivo.

[Study on the animal model for severe acute respiratory syndrome].

To screen small animals susceptible to SARS-CoV, five species of animals, including guinea pig, hamster, albino hamster, chicken and rat, were experimentally infected with SARS-CoV strain BJ-01 by different routes. On the basis of this, further cynomolgus and rhesus macaques were selected and experimentally inoculated SARS-CoV, the quality they serve as animal model for SARS was evaluated. The results showed that, all five species of small animals chosed were not susceptible to SARS-CoV, no characterized changes in clinical sign and histopathology were observed after infection, but from the lung samples of large rat and pig guinea, the genomic RNA of SARS-CoV could be detected by RT-PCR at day 14 post infection, this suggested that SARS-CoV could replicate in these animals. After inoculated with SARS-CoV, all inoculated cynomolgus and rhesus macaques had developed interstitial pneumonia of differing severity. These changes on histopathology were similar to that seen in SARS patients, but the pathological lesions were less severe than that of human. Except interstitial pneumonia, no other characterized pathological changes were observed. This suggested cynomolgus and rhesus macaques were not the ideal animal model for SARS in fact, but they could serve as animal model for SARS when a more ideal animal model is absent.

Rutin inhibits ß-amyloid aggregation and cytotoxicity, attenuates oxidative stress, and decreases the production of nitric oxide and proinflammatory cytokines.

Alzheimer's disease (AD) is a complex, multi-factorial neurodegenerative disease. The aggregation of soluble ß-amyloid (Aß) into fibrillar deposits is a pathological hallmark of AD. The Aß aggregate-induced neurotoxicity, inflammatory reactions, oxidative stress, and nitric oxide (NO) generation are strongly linked to the etiology of AD. Here, we show that the common dietary flavonoid, rutin, can dose-dependently inhibit Aß42 fibrillization and attenuate Aß42-induced cytotoxicity in SH-SY5Y neuroblastoma cells. Moreover, rutin decreases the formation of reactive oxygen species (ROS), NO, glutathione disulfide (GSSG), and malondialdehyde (MDA), reduces inducible nitric oxide synthase (iNOS) activity, attenuates mitochondrial damage, increases the glutathione (GSH)/GSSG ratio, enhances the activities of super oxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), and modulates the production of proinflammatory cytokines by decreasing TNF-α and IL-1ß generation in microglia. Taken together, the actions of rutin on multiple pathogenic factors deserves further investigation for the prevention and treatment of AD.

[Animal experimental study of compression anastomosis ring for low anterior resection].

OBJECTIVE: To evaluate the feasibility and safety of nickel-titanium compression anastomosis ring (CAR27) in colorectal anastomosis after low anterior rectal resection in animal models. METHODS: End-to-end colorectal anastomosis was performed using CAR27 in 6 experimental pigs after resection of the middle and lower third of the rectum. The animals were observed postoperatively for up to 56 days. Five pigs were sacrificed at day 14 and the other at day 56. Distance from anal verge to anastomosis and anastomotic circumference were measured. Histopathologic examination was performed. RESULTS: The median distance from anal verge was 5.3(4-6) cm. No anastomotic leak or other complications were observed. All the pigs recovered and gained weight. In 5 animals sacrificed at day 14, the mean circumference of the anastomosis was 6.8(6.5-7.0) cm, and histopathological examination showed mild inflammatory reaction and fibrosis. In the one sacrificed at day 56, the circumference expanded to 9.3 cm, and no inflammation and fibrosis were observed. Minor adhesion was noticed in only one pig, while smooth and intact serosa in the anastomosis was seen in the rest of the animals. CONCLUSION: CAR27 is a promising device for mid and low colorectal anastomosis.

Aß1-16 can aggregate and induce the production of reactive oxygen species, nitric oxide, and inflammatory cytokines.

Amyloid-ß (Aß40/42) aggregates containing the cross-ß-sheet structure are associated with the pathogenesis of Alzheimer's disease (AD). It is generally accepted that the N-terminal peptide of Aß40/42, Aß1-16, does not aggregate, and is not cytotoxic. However, we here show that Aß1-16 can aggregate, and form cytotoxic aggregates containing ß-turns and regular non-amyloid ß-sheet structures. Factors such as pH, ionic strength, and agitation were found to influence Aß1-16 aggregation, and the amino acid residues Asp1, His6, Ser8, and Val12 in Aß1-16 may play a role in this aggregation. Our MTT results showed that Aß1-16 monomers or oligomers were toxic to SH-SY5Y cells, but Aß1-16 fibrils exhibited less cytotoxicity. Our studies also indicate that Aß1-16 aggregates can increase the formation of reactive oxygen species and nitric oxide, induce the loss of calcium homeostasis, and incur the microglial production of TNF-α and IL-4. Thus, our findings suggest that Aß1-16 may contribute to AD pathogenesis.