Collagen degradation and neutrophilic infiltration: a vicious circle in inflammatory bowel disease

Cellular mechanisms in basic and clinical gastroenterology and hepatolog

Analysis of poly(styrene-co-methyl acrylate) and poly(styrene-co-butyl acrylate) by high-performance liquid chromatography

Poly(styrene—co-methyl acrylate) and poly(styrene—co-butyl acrylate) were separated according to their chemical composition by gradient elution. The chromatographic separation on silica was optimized for a gradient ranging from n-heptane as a non-solvent to dichloromethane containing a small amount of methanol as a strong solvent. The influence of different stationary phases, the chemical composition and molecular mass on the separation of the copolymers was investigated. From the results of different chromatographic and turbidimetric experiments it is concluded that the copolymer separation is controlled by both precipitation and adsorption mechanisms. The contribution of adsorption processes to the separation is only advantageous when normal-phase gradients are applied

Analysis of poly(styrene-co-methyl acrylate) and poly(styrene-co-butyl acrylate) by high-performance liquid chromatography

Poly(styrene—co-methyl acrylate) and poly(styrene—co-butyl acrylate) were separated according to their chemical composition by gradient elution. The chromatographic separation on silica was optimized for a gradient ranging from n-heptane as a non-solvent to dichloromethane containing a small amount of methanol as a strong solvent. The influence of different stationary phases, the chemical composition and molecular mass on the separation of the copolymers was investigated. From the results of different chromatographic and turbidimetric experiments it is concluded that the copolymer separation is controlled by both precipitation and adsorption mechanisms. The contribution of adsorption processes to the separation is only advantageous when normal-phase gradients are applied

Melphalan antitumor efficacy and hepatotoxicity: The effect of variable infusion duration in the hepatic artery

The optimum conditions (duration and concentration) of a fixed dose, intra-arterial melphalan infusion in relation to its antitumor effect and toxicity in the liver were investigated in a rat colon tumor model (CC531) of liver metastases. We studied the difference in tumor and liver uptake, as well as antitumor effect and hepatotoxicity after 5- and 20-min hepatic arterial infusion (HAI) of a fixed melphalan dose. Melphalan content in perfusate, liver, and tumor tissue was analyzed by high-performance liquid chromatography. The antitumor effect and hepatotoxicity in rats treated either systemically or with 5- and 20-min HAI, with a fixed dose melphalan (4.4 μmol), were assessed 2 weeks after treatment. No difference in melphalan content of tumor/ liver tissue or antitumor effect was observed between rats treated with 5- and 20-min HAI. Hepatotoxicity was strongly affected by perfusion duration/concentration, however. Rats treated with 5-min HAI weighed significantly less, and liver toxicity parameters were significantly increased compared with those of all other groups; eight of nine rats showed severe cholangiofibrosis. Body weights and liver toxicity parameters of the rats treated with 20-min HAI were not statistically different from the control group. In conclusion, duration of HAI with 4.4 μmol of fixed dose melphalan did not affect tumor uptake and antitumor effect, but the resulting increase in melphalan concentration had major impact on hepatobiliary toxicity. Therefore, in a clinical setting, caution should be taken when infusion duration and concentration of melphalan are changed

Increased oral availability and brain accumulation of the ALK inhibitor crizotinib by coadministration of the P-glycoprotein (ABCB1) and breast cancer resistance protein (ABCG2) inhibitor elacridar.

Contains fulltext : 138290.pdf (Publisher’s version ) (Closed access)Crizotinib is an oral tyrosine kinase inhibitor approved for treating patients with non-small cell lung cancer (NSCLC) containing an anaplastic lymphoma kinase (ALK) rearrangement. We used knockout mice to study the roles of P-glycoprotein (ABCB1) and breast cancer resistance protein (ABCG2) in plasma pharmacokinetics and brain accumulation of oral crizotinib, and the feasibility of improving crizotinib kinetics using coadministration of the dual ABCB1/ABCG2 inhibitor elacridar. In vitro, crizotinib was a good transport substrate of human ABCB1, but not of human ABCG2 or murine Abcg2. With low-dose oral crizotinib (5 mg/kg), Abcb1a/1b(-/-) and Abcb1a/1b;Abcg2(-/-) mice had an approximately twofold higher plasma AUC than wild-type mice, and a markedly (~40-fold) higher brain accumulation at 24 hr. Also at 4 hr, crizotinib brain concentrations were approximately 25-fold, and brain-to-plasma ratios ~14-fold higher in Abcb1a/1b(-/-) and Abcb1a/1b;Abcg2(-/-) mice than in wild-type mice. High-dose oral crizotinib (50 mg/kg) resulted in comparable plasma pharmacokinetics between wild-type and Abcb1a/1b(-/-) mice, suggesting saturation of intestinal Abcb1. Nonetheless, brain accumulation at 24 hr was still ~70-fold higher in Abcb1a/1b(-/-) than in wild-type mice. Importantly, oral elacridar coadministration increased the plasma and brain concentrations and brain-to-plasma ratios of crizotinib in wild-type mice, equaling the levels in Abcb1a/1b;Abcg2(-/-) mice. Our results indicate that crizotinib oral availability and brain accumulation were primarily restricted by Abcb1 at a non-saturating dose, and that coadministration of elacridar with crizotinib could substantially increase crizotinib oral availability and delivery to the brain. This principle might be used to enhance therapeutic efficacy of crizotinib against brain metastases in NSCLC patients

Impact of P-glycoprotein (ABCB1) and breast cancer resistance protein (ABCG2) gene dosage on plasma pharmacokinetics and brain accumulation of dasatinib, sorafenib, and sunitinib.

Item does not contain fulltextLow brain accumulation of anticancer drugs due to efflux transporters may limit chemotherapeutic efficacy, necessitating a better understanding of the underlying mechanisms. P-glycoprotein (Abcb1a/1b) and breast cancer resistance protein (Abcg2) combination knockout mice often display disproportionately increased brain accumulation of shared drug substrates compared with single transporter knockout mice. Recently developed pharmacokinetic models could explain this phenomenon. To experimentally test these models and their wider relevance for tyrosine kinase inhibitors and other drugs, we selected dasatinib, sorafenib, and sunitinib because of their divergent oral availability and brain accumulation profiles: the brain accumulation of dasatinib is mainly restricted by Abcb1, that of sorafenib mainly by Abcg2, and that of sunitinib equally by Abcb1 and Abcg2. We analyzed the effect of halving the efflux activity of these transporters at the blood-brain barrier by generating heterozygous Abcb1a/1b;Abcg2 knockout mice and testing the plasma and brain levels of the drugs after oral administration at 10 mg/kg. Real-time reverse transcription-polymerase chain reaction analysis confirmed the approximately 2-fold decreased expression of both transporters in brain. Interestingly, whereas complete knockout of the transporters caused 24- to 36-fold increases in brain accumulation of the drugs, the heterozygous mice only displayed 1.6- to 1.9-fold increases of brain accumulation relative to wild-type mice. These results are well in line with the predictions of the pharmacokinetic models and provide strong support for their validity for a wider range of drugs. Moreover, retrospective analysis of fetal accumulation of drugs across the placenta in Abcb1a/1b heterozygous knockout pups suggests that these models equally apply to the maternal-fetal barrier.1 september 201