Establishment of in vitro methods for evaluation of induction and inhibition of human CYP450 enzymes by drugs / 药学学报

The aim of this study is to establish the in vitro methods for the study of induction and inhibition on CYP450 by drugs, and to validate the analytical method and incubation system. A method for the simultaneous determination of eight metabolites of seven subtypes of CYP450 enzymes probe substrates in human liver microsomes (HLM) was established and validated. The incubation system was optimized to confirm the incubation time and protein concentration of HLM, the enzyme activity of seven subtypes of CYP450 enzymes in HLM was determined, and the inhibition effects on each CYP450s were checked by positive controls. The method for the simultaneous determination of three metabolites of subtypes of CYP450 enzymes was established and validated in human primary cultured hepatocytes (HPCH) using the incubation medium. The enzyme activity of three subtypes of CYP450 enzymes in HPCH was determined, and the total RNA was extracted from HPCH after incubation. The expression of CYP450 enzymes were measured by Taqman fluorescence probe method. The induction effects on each CYP450s were examined using the positive controls. The established methods for the determination of metabolites of probe substrates were fully validated, and the results were conformed to the requirements of bioanalytical method validation. The induction and inhibition effects on each CYP450s were checked by positive controls. The established in vitro methods for the study of drug induction and inhibition on CYP450 were simple and reliable, which could be used in the investigation of enzyme induction or inhibition properties of new drug candidates and to evaluation the metabolic interactions of concomitant medication in clinical.

Study on induction of rat liver cytochrome P450 enzymes by bencycloquidium bromide / 中国药学杂志

OBJECTIVE: To study the induction effect of bencycloquidium bromide (BCQB) on rat liver cytochrome P450 enzymes. METHODS: Rats were divided into solvent control group, positive control (phenobarbital) group and BCQB group. The rats in BCQB groups were intranasally administered with 1, 3, and 9 mg · kg-1 BCQB, respectively. After multiple-dose administration, the rats were sacrificed, and the livers were weighed and prepared to microsomes. Then the liver coefficients were calculated, and the total content of CYP450 enzymes in liver microsomes was determined by spectrophotometer. HPLC-MS/MS method was adopted and validated to simultaneously determine the productive velocity of 6β-hydroxyl testosterone and paracetamol after incubation of rat liver microsomes. The activities of CYP1A1/2 and CYP3A1/2 were measured according to the productive velocity. RESULTS: The liver coefficients, total content of CYP450 enzymes, and activity of CYP1A1/2 were significantly different (P0.05) between solvent control group and BCQB groups. The activity of CYP3A1/2 in BCQB groups was not higher than solvent control group. CONCLUSION: Phenobarbital has induction effect on rat liver CYP450 enzymes. The test system can be used to evaluate the induction effect of BCQB on rat liver CYP450 enzymes. BCQB has no induction effect on liver CYP450 enzymes in rats.

Effect of hyperbaric oxygen preconditioning on spleen lymphocytes and cell adhesion molecules after skin transplantation in mice / 中国实验血液学杂志

The aim of this study was to explore the effect of hyperbaric oxygen (HBO) preconditioning on the rejection of skin allograft in mice and its molecular mechanism. BALB/c donor mice and C57BL/6 recipients received hyperbaric oxygen preconditioning once a day for 7 days. After skin transplantation, the recipients were treated with cyclosporine A (CsA) intraperitoneally. Immunofluorescent staining technique and flow cytometry were used to observe the influence HBO on percentage of spleen lymphocytes CD3+, CD4+, CD8+ and cell adhesion molecule LFA-1 (CD11a/CD18). The results showed that as compared with control, the numbers of CD3+, CD4+, CD8+, CD4+CD11a+, CD4+ CD18+, CD8+CD11a+, CD8+CD18+ lymphocytes of spleen decreased in HBO preconditioning groups and CsA group, and decreased markedly in HBO preconditioning combined with CsA group (p<0.05); the general state of recipient mice in HBO preconditioning combined with CsA group was better than that of recipient mice received HBO preconditioning or CsA only. It is concluded that the method of HBO preconditioning combined with traditional immunosuppressive agent CsA has remarkable advantage in inhibiting the rejection of skin graft. Its molecular protective mechanism is correlated with the expression of adhesive molecules on T cell subsets.

Screening of effective shRNA targeting TNF-alpha and constructing of recombinant plasmid / 中国实验血液学杂志

The objective of this study was to screen out the effective shRNA which can inhibit the gene expression of tumour necrosis factor-alpha (TNF-alpha), to construct the recombinant plasmid and to determine its sequence so as to provide the new approach for searching gene therapy of TNF-alpha related diseases. The primary macrophages were added into 15% DMEM, then cells were adjusted as 2 x 10(7) cells/L and were inoculated in 6-well plate with 3 ml/well, and were cultured at 37 degrees C in a fully humidified atmosphere with 5% CO(2). Cells were stimulated with lipopolysaccharide (LPS) and the concentration of TNF-alpha in the supernatant at different time points was determined by enzyme-linked immunosorbent assay (ELISA). The 5 synthesized DNA sequences which can be transcripted into shRNA were transfected into cells with lipofectamine 2000, then the cells were stimulated with LPS for 24 hours. The concentration of TNF-alpha in the supernatant and the expression of TNF-alpha mRNA were determined by ELISA and reverse transcription polymerase chain reaction (RT-PCR) respectively. The most effective shRNA was inserted into plasmid, and the recombinant plasmid was identified by sequence analysis. The results showed that the concentration of TNF-alpha in the supernatant reached peak after the stimulation with LPS for 24 hours. In the RNA interference group, the shRNA 1 was the most effective one, which could inhibit the expression of TNF-alpha by 59.46% and the expression of TNF-alpha mRNA by 61.2%. The recombinant plasmid was cloned and the sequence of interest was obtained. In conclusion, the most effective shRNA targeting TNF-alpha was successfully screened out and the recombinant plasmid was constructed. The recombinant plasmid may be helpful to search new gene therapy for TNF-alpha related disease.

Effect of hyperbaric oxygen on acute graft-versus-host disease after allogeneic bone marrow transplantation / 中国实验血液学杂志

The objective of this study was to investigate the function and mechanism of hyperbaric oxygen (HBO) in antagonizing acute graft-versus-host disease (aGVHD) and improving the rate of survival. The lethally irradiated C57BL/6 recipients were injected with bone marrow and lymphocyte of spleen from BALB/c donors and were treated with HBO, cyclosporine A (CsA) and methotrexate (MTX). T lymphocytes and subsets, adhesion molecules and cytokines were detected by flow cytometry, ELISA and RT-PCR respectively. The results showed that the survival rate in HBO group was much higher than that in allogenetic bone marrow transplantation (allo-BMT) group and CsA + MTX group; the numbers of CD3(+), CD4(+), CD8(+), CD4(+)CD11a(+), CD4(+)CD18(+), CD8(+)CD11a(+), CD8(+)CD18(+) lymphocytes in spleen were decreased markedly by HBO and CsA + MTX (p < 0.05); the levels of IL-2 and TNFalpha mRNA and their serum concentrations in HBO group were much lower than those in allo-BMT group but were higher than those in CsA + MTX group; the levels of IL-4 and IL-10 mRNA in HBO group were much higher than those in allo-BMT group and CsA + MTX group. It is concluded that HBO has more remarkable advantage in improving the rate of survival than CsA + MTX, its mechanism of anti-aGVHD is tightly correlated with the transform of T cell and its subsets and the expression of adhesion molecules and cytokines.