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Chang-Xiao Liu

Publications and source records attributed to Chang-Xiao Liu.

5 recordsLinked to original sources
PubMed2006

Intestinal permeability of metformin using single-pass intestinal perfusion in rats.

AIM: To characterize the intestinal transport and mechanism of metformin in rats and to investigate whether or not metformin is a substrate for P-glycoprotein (P-gp). METHODS: The effective intestinal permeability of metformin was investigated using single-pass intestinal perfusion (SPIP) technique in male Waster rats. SPIP was performed in three isolated intestinal segments (duodenum, jejunum and ileum) at the same concentration of metformin (50 microg/mL) to test if the intestinal transport of metformin exhibited site-dependent changes, and in a same isolated intestinal segment (duodenal segment) at three different concentrations of metformin (10, 50, 200 microg/mL) to test if the intestinal transport of metformin exhibited concentration-dependent changes. Besides, P-gp inhibitor verapamil (400 microg/mL) was co-perfused with metformin (50 microg/mL) in the duodenum segment to find out if the intestinal absorption of metformin was affected by P-gp exiting along the gastrointestinal track. Stability studies were conducted to ensure that the loss of metformin could be attributed to intestinal absorption. RESULTS: The effective permeability values (P(eff)) of metformin in the jejunum and ileum at 50 microg/mL were significantly lower than those in the duodenum at the same concentration. Besides, P(eff) values in the duodenum at high concentration (200 microg/mL) were found to be significantly lower than those at low and medium concentrations (10 and 50 microg/mL). Moreover the co-perfusion with verapamil did not increase the P(eff) value of metformin at 50 microg/mL in the duodenum. CONCLUSION: Metformin could be absorbed from the whole intestine, with the main absorption site at duodenum. This concentration-dependent permeability behavior in the duodenum indicates that metformin is transported by both passive and active carrier-mediated saturable mechanism. The P(eff) value can not be increased by co-perfusion with verapamil, indicating that absorption of metformin is not efficiently transported by P-gp in the gut wall. Furthermore metformin is neither a substrate nor an inducer of P-gp. Based on the P(eff) values obtained in the present study and using established relationships, the human fraction dose absorbed for metformin is estimated to be 74%-90% along human intestine.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2006

[Application of new method for data processing in metabonomic studies].

AIM: To search for and application of new method for data processing in metabonomic studies. METHODS: The paper proposed that in the processing of metabonomic data, robust PCA method can be used to diagnose outliers; and unstable variables judged by comparison between difference within class and difference among classes should be excluded before data analysis; moreover, the data should be properly scaled before further processing. The proposed methods were used to preprocess metabolomic data of four genotypes of the Arabidopsis thaliana plants. RESULTS AND CONCLUSION: The outcome demonstrated that the application of these methods can obviously improve clustering and biomarker identifying results.

Algorithms↗
PubMed2005

Tissue distribution and excretion of 125I-lidamycin in mice and rats.

AIM: To investigate the tissue distribution, urinary and fecal excretions of (125)I-lidamycin ((125)I-C-1027) in mice and its biliary excretion in rats. METHODS: The total radioactivity assay (RA method) and the radioactivity assay after precipitation with 200 mL/L trichloroacetic acid (TCA-RA method) were used to determine the tissue distribution, and the urinary and fecal excretions of (125)I-C-1027 in mice and its biliary excretion in rats. RESULTS: Tissue concentrations reached the peak at the fifth minute after administration of (125)I-C-1027 to mice. The highest concentration was in kidney, and the lowest in brain at all test-time points. The organs of the concentrations of (125)I-C-1027 from high to low were kidney, lung, liver, stomach, spleen, uterus, ovary, intestine, muscle, heart, testis, fat, and brain in mice. The accumulative excretion amounts of 0-24 h, and 0-96 h after administration of (125)I-C-1027 were 68.36 and 71.64% in urine, and 2.60 and 3.21% in feces of mice, respectively, and the accumulative excretion amount of 0-24 h was 3.57% in bile in rats. CONCLUSION: Our results reflect the characteristics of the tissue distribution, urinary and fecal excretions of (125)I-C-1027 in mice and the biliary excretion of (125)I-C-1027 and its metabolites in rats, and indicate that (125)I-C-1027 and its metabolites are mainly distributed in kidney, and excreted in urine.

Aminoglycosides↗
PubMed2005

Pharmacokinetics of C-1027 in mice as determined by TCA-RA method.

AIM: To validate a radioactivity assay, the TCA-RA method, for the measurement of C-1027 in serum and to evaluate its application in determination of pharmacokinetics of C-1027 in mice. METHODS: (125)I-C-1027 was prepared by the Iodogen method and separated by HPLC. The radioactivity assay was established and used to determine (125)I-C-1027 in mice at doses of 10, 50 and 100 microg/kg after precipitation with 20% trichloroacetic acid (TCA-RA method). Several pharmacokinetic parameters were determined after intravenous injection of (125)I-C-1027 to mice. RESULTS: After intravenous injection of (125)I-C-1027 to mice, at doses of 10, 50 and 100 microg/kg; the apparent distribution volumes (V(d)) were 0.26, 0.31 and 0.33 L/kg; the biological half-lives (T(1/2)) were 3.10, 3.40 and 3.90 h; the areas under curve (AUC) were 18.41, 103.69 and 202.74 ng/h/mL; the elimination rate constants (K) were 1.04, 1.26 and 0.58/h; and the total body clearance (Cl) were 0.54, 0.48 and 0.49 L/kg/h, respectively. CONCLUSION: TCA-RA is a sensitive, reliable and suitable method for the determination of (125)I-C-1027 in mouse serum.

Aminoglycosides↗