Examination of drug metabolism using human hepatocytes is important in the early stages of drug development. However, primary human hepatocytes are short-lived and cannot be maintained in culture over the long term. Considerable donor-dependent variations are also problematic. Human embryonic stem (ES) cells are pluripotent cells derived from the inner cell mass of blastocysts and are capable of differentiating into three embryonic germ layers and germ cells.1) The cells apparently differentiate into various types of mature cells, and are thereby an attractive source for routine access to large numbers of cells that can be used for the development of candidate drug-screening strategies replacing primary cells.2) However, ethical considerations have limited the availability of human ES cells. The phenotype of human ES cells is known to be similar to that of monkey ES cells but differs from that of mouse ES cells with regard to morphology, response to leukemia inhibitory factor, and gene expression patterns. 1,[3][4][5] Research using monkey ES cells is considered to be useful for investigation of differentiation mechanisms in primate ES cells and models of human ES cells. Recently, it has been shown that monkey ES cells can be differentiated into various cell types-including neurons, hematopoietic cells, and pancreatic cells-using growth factors. [6][7][8] Hepatocytes derived from monkey ES cells may be useful for pharmacokinetic examinations such as induction of drug metabolism enzymes and interactions of candidate drugs. To date however, there have been few reported studies describing the differentiation of monkey ES cells into hepatocytes. 9,10) After the emergence of the liver bud from the developing gut tube, the level of hepatic maturation is characterized by the expression of liver-and stage-specific genes. For example, alfa-fetoprotein (AFP) is an early hepatic marker, expressed by hepatoblasts in the liver bud until birth.11,12) The synthesis of AFP decreases dramatically after birth and only trace amounts are expressed in the adult liver. In contrast, albumin (ALB), the most abundant protein synthesized by hepatocytes, is initially expressed at lower levels in early fetal hepatocytes but this increases as the hepatocytes mature, reaching a maximum in adult hepatocytes. 13,14) The mRNA expression of cytochrome P450 7A1 (CYP7A1) which is a rate-limiting enzyme in the conversion of cholesterol to bile acids in liver 15) is detected in fetal liver of third trimester of pregnancy.16) After birth, CYP7A1 increases several-fold with age both at the enzyme activity level and the mRNA level. 17,18) The in vitro approaches involve the formation of embryoid bodies (EBs) to mimic the inductive microenvironment required for liver organogenesis [19][20][21] and treatment with specific growth factors and cytokines critical for hepatic differentiation.22) At present, culture systems for ES cells have mainly used gelatin-or collagen-coated plates as the matrix for the maintenance of cells in an undifferentiated state an...
Hepatocyte differentiation markers were expressed in the cells differentiated from mouse embryonic stem (ES) cells. In the differentiating ES cells, Cyp1a1 mRNA was highly expressed during the early to middle stage; Cyp2c29, Cyp2e1, Cyp3a11 and Cyp7a1 mRNAs were expressed only at the late stage; Cyp7b1 mRNA was expressed throughout all stages. Alpha-fetoprotein and albumin were co-expressed with Cyp3a and Cyp1a, respectively. Aryl hydrocarbon receptor, aryl hydrocarbon receptor nuclear translocator and glucocorticoid receptor mRNAs were detected in differentiating ES cells throughout the culture period. Pregnane X receptor mRNA was detected only in cells cultured for more than 24 days. The expression levels of Cyp2c29, Cyp3a11 and Cyp7a1 and G6p mRNAs were increased in embryoid bodies that were cultured with culture medium containing acid fibroblast growth factor, hepatocyte growth factor (HGF) and oncostatin M for 12 or 18 days, then the medium was replaced by that without HGF. These findings suggested that the expression levels of Cyp genes in hepatocytes differentiated from ES cells were markedly changed in individual enzymes during the course of differentiation, and that the duration of incubation with the addition of HGF affected the expression of Cyps and hepatocytes marker proteins.
BackgroundEffect of statin therapy has been reported to be associated with patient’s adherence. Atorvastatin was available in Japan as a brand-name product beginning in 2000. The first atorvastatin generics were introduced in Japan in November 2011. The objective of this study was to analyze whether changing from a brand-name atorvastatin to a generic product would affect patient adherence.MethodsWe conducted a retrospective cohort study that included adult patients who received newly prescribed brand-name atorvastatin between June 1, 2011 and May 31, 2012, using a health insurance claims database in Japan. Patients were classified by the presence or absence of changing to a generic during the 6 months from December 1, 2011 to May 31, 2012 (the index period). The first prescription date for the generic or brand product during the index period was defined as the index date. Adherence to therapy was assessed by the proportion of days covered (PDC) and persistence of treatment by time to discontinuation.ResultsThere were 135 patients changing to generic atorvastatin and 147 continuing with the brand-name product. There was no significant difference in decrease of PDC from pre- to post-index date between the changed cohort and continued cohort (−8.6% vs −10.3%, respectively; P = 0.443). After adjusting for baseline covariates, including adherence in pre-index date, no statistically significant differences were observed in the adjusted odds of adherence between the cohorts (adjusted odds ratio = 0.83, 95% confidence interval (CI) = 0.46–1.53). There was also no significant difference in persistence between two cohorts in the 180-day after post-index date. After analysis of a Cox proportional hazard regression model controlling for baseline covariates, including adherence in pre-index date, no statistically significant differences were observed for the hazard of non-persistence between the cohorts (adjusted hazard ratio = 0.96, 95% CI = 0.60–1.53).ConclusionsChanging from a brand-name atorvastatin to generic product did not affect adherence for patients newly treated with atorvastatin.
Abstract. In this study we report the pharmacokinetics and severe adverse effects of sunitinib in a woman with a gastrointestinal stromal tumor (GIST). A 60-year-old woman with small intestinal GIST developed severe thrombocytopenia (1.7x10 4 /µl) following 1 week of treatment with sunitinib at 50 mg/day. Although the dose of sunitinib was reduced to 25 mg/day, platelet levels remained low. On day 7, the trough concentration of sunitinib plus SU12662 was 46.1 ng/ml and the area under the curve (AUC) was 1,393.0 ng·h/l. The dose was again reduced to 12.5 mg/day. However, the day after resumption of treatment, the patient developed symptoms of left heart failure due to myocardosis caused by sunitinib. Sunitinib has been reported to inhibit platelet-derived growth factor receptor (PDGFR) phosphorylation at concentrations over the range of 50-100 ng/ml (sunitinib plus SU12662) in vivo. In this case, the plasma concentration was sufficient to inhibit PDGFR at 25 or 50 mg/day. However, thrombocytopenia appeared at both dosages. Although the results in this case did not suggest a correlation between thrombocytopenia and plasma concentration, the degree of thrombocytopenia was decreased by reduction of the dose. In conclusion, the findings reported here indicate that the plasma concentration of sunitinib plus SU12662 is an important indicator to reduce adverse effects.
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