Correcting QUEST Magnetic Resonance Imaging–Sensitive Free Radical Production in the Outer Retina In Vivo Does Not Correct Reduced Visual Performance in 24-Month-Old C57BL/6J Mice

PurposeTo test the hypothesis that acutely correcting a sustained presence of outer retina free radicals measured in vivo in 24-month-old mice corrects their reduced visual performance.MethodsMale C57BL/6J mice two and 24 months old were noninvasively evaluated for unremitted production of paramagnetic free radicals based on whether 1/T1 in retinal laminae are reduced after acute antioxidant administration (QUEnch-assiSTed [QUEST] magnetic resonance imaging [MRI]). Superoxide production was measured in freshly excised retina (lucigenin assay). Combining acute antioxidant administration with optical coherence tomography (i.e., QUEST OCT) tested for excessive free radical–induced shrinkage of the subretinal space volume. Combining antioxidant administration with optokinetic tracking tested for a contribution of uncontrolled free radical production to cone-based visual performance declines.ResultsAt two months, antioxidants had no effect on 1/T1 in vivo in any retinal layer. At 24 months, antioxidants reduced 1/T1 only in superior outer retina. No age-related change in retinal superoxide production was measured ex vivo, suggesting that free radical species other than superoxide contributed to the positive QUEST MRI signal at 24 months. Also, subretinal space volume did not show evidence for age-related shrinkage and was unresponsive to antioxidants. Finally, visual performance declined with age and was not restored by antioxidants that were effective per QUEST MRI.ConclusionsAn ongoing uncontrolled production of outer retina free radicals as measured in vivo in 24 mo C57BL/6J mice appears to be insufficient to explain reductions in visual performance.     

A Novel Model of Urinary Tract Differentiation,Tissue Regeneration,and Disease: Reprogramming Human Prostate and Bladder Cells into Induced Pluripotent Stem Cells

Background

Primary culture and animal and cell-line models of prostate and bladder development have limitations in describing human biology, and novel strategies that describe the full spectrum of differentiation from foetal through to ageing tissue are required. Recent advances in biology demonstrate that direct reprogramming of somatic cells into pluripotent embryonic stem cell (ESC)-like cells is possible. These cells, termed induced pluripotent stem cells (iPSCs), could theoretically generate adult prostate and bladder tissue, providing an alternative strategy to study differentiation.

Objective

To generate human iPSCs derived from normal, ageing, human prostate (Pro-iPSC), and urinary tract (UT-iPSC) tissue and to assess their capacity for lineage-directed differentiation.

Design, setting, and participants

Prostate and urinary tract stroma were transduced with POU class 5 homeobox 1 (POU5F1; formerly OCT4), SRY (sex determining region Y)-box 2 (SOX2), Kruppel-like factor 4 (gut) (KLF4), and v-myc myelocytomatosis viral oncogene homolog (avian) (MYC, formerly C-MYC) genes to generate iPSCs.

Outcome measurements and statistical analysis

The potential for differentiation into prostate and bladder lineages was compared with classical skin-derived iPSCs. The student t test was used.

Results and limitations

Successful reprogramming of prostate tissue into Pro-iPSCs and bladder and ureter into UT-iPSCs was demonstrated by characteristic ESC morphology, marker expression, and functional pluripotency in generating all three germ-layer lineages. In contrast to conventional skin-derived iPSCs, Pro-iPSCs showed a vastly increased ability to generate prostate epithelial-specific differentiation, as characterised by androgen receptor and prostate-specific antigen induction. Similarly, UT-iPSCs were shown to be more efficient than skin-derived iPSCs in undergoing bladder differentiation as demonstrated by expression of urothelial-specific markers: uroplakins, claudins, and cytokeratin; and stromal smooth muscle markers: α-smooth-muscle actin, calponin, and desmin. These disparities are likely to represent epigenetic differences between individual iPSC lines and highlight the importance of organ-specific iPSCs for tissue-specific studies.

Conclusions

IPSCs provide an exciting new model to characterise mechanisms regulating prostate and bladder differentiation and to develop novel approaches to disease modelling. Regeneration of bladder cells also provides an exceptional opportunity for translational tissue engineering.     

Paraoxonase-1 activity affects the clopidogrel response in CYP2C19 loss-of-function carriers

Background

The impact of paraoxonase-1 (PON1) activity on the response to clopidogrel may differ in patients treated with drug-eluting stents (DES) in association with CYP2C19 loss-of-function (LOF) polymorphisms.

Methods

This study included 112 Japanese patients receiving clopidogrel (75 mg/day) and aspirin (100 mg/day) who underwent optical coherence tomography (OCT) examination 9 months after DES implantation. The CYP2C19 genotype was analyzed and LOF carriers (*1/*2, *1/*3, *2/*2, *3/*3, *2/*3) were identified. At the 9-month follow-up, platelet reactivity was determined by measuring the P2Y12 reactivity unit (PRU) using a VerifyNow P2Y12 assay, PON1 activity was evaluated and intra-stent thrombus was evaluated by OCT.

Results

Of the 112 Japanese patients, 75 were LOF carriers (67.0%). The patients were divided into tertiles according to the PON1 activity (tertile 1; < 230 U/L, tertile 2; 230–283 U/L, tertile 3; > 283 U/L). In the VerifyNowP2Y12 analysis, tertile 1 had a higher PRU than tertiles 2 and 3 in LOF carriers, and there was no difference among tertiles in non-carriers. The highest incidence of intra-stent thrombus was observed in tertile 1 followed by tertiles 2 and 3 in LOF carriers, whereas there was no such difference in non-carriers. Multivariate analysis revealed that LOF carriers and PON1 activity tertile 1 were independent predictors of intra-stent thrombus in all patients. In LOF carriers, tertile 1 was the only independent predictor for intra-stent thrombus.

Conclusion

Low PON1 activity is associated with a low response to clopidogrel and a high frequency of intra-stent thrombus only in LOF carriers.     

Renal vectorial transport of berberine mediated by organic cation transporter 2 (OCT2) and multidrug and toxin extrusion proteins 1 (MATE1) in rats

Berberine, a well‐known plant alkaloid derived from Rhizoma coptidis, has potential applications as a therapeutic drug for diabetic nephropathy. However, the transporter‐mediated renal transport of berberine remains largely unclear. This study aimed to investigate the renal transport mechanism of berberine using transfected cells, kidney slices and animal experiments. In Madin‐Darby canine kidney (MDCK) cells stably expressing rat OCT2 (MDCK‐rOCT2) and kidney slices, saturable and non‐saturable uptake of berberine was observed, and corticosterone could inhibit the uptake of berberine, with IC₅₀ values of 0.1 μm and 147.9 μm , respectively. In double‐transfected cells, the cellular accumulation of berberine into MDCK‐rOCT2 and MDCK‐rOCT2‐rMATE1 (MDCK cells stably expressing rOCT2 and rMATE1) cells was significantly higher than the uptake into MDCK cells. Meanwhile, berberine transcellular transport was considerably higher in double‐transfected MDCK‐rOCT2‐rMATE1 cells than in MDCK and MDCK‐rOCT2 cells. Corticosterone for MDCK‐rMATE1 and MDCK‐MDR1 and pyrimethamine for MDCK‐rMATE1 at high concentrations could inhibit the efflux of berberine. In animal experiments, compared with the berberine alone group, the cumulative urinary excretion of berberine significantly decreased in the corticosterone or pyrimethamine pretreatment groups. In the rat kidney, pyrimethamine increased, and a low dose of corticosterone (5 mg/kg) decreased, the berberine concentration. However, there was no apparent change in the renal concentration of berberine in rats pretreated with corticosterone (10 or 20 mg/kg). Thus, berberine is not only a substrate of OCT2 and P‐glycoprotein, but is also a substrate of MATE1. Both OCT2 and MATE1 mediate the renal vectorial transport of berberine.     

miR-203a-3p通过ALOX15途径抑制胃癌细胞铁死亡

目的探讨miR-299-3p靶向调控OCT4B1对结直肠癌细胞SW480增殖、迁移、侵袭及凋亡的作用。 方法将SW480细胞分为NC组、mimics组、inhibitor组,采用MTT法检测细胞活力,结晶紫染色检测单克隆形成数,流式细胞术检测细胞凋亡,Transwell实验检测细胞侵袭能力,qRT-PCR测定细胞miR-299-3p和OCT4B1 mRNA,蛋白免疫印迹法测定OCT4B1蛋白表达。荧光素酶报告基因检测miR-556-3p对SW480细胞OCT4B1活性的调控作用。 结果与NC组比较,miR-299-3p水平、细胞凋亡率mimics组升高,inhibitor组降低,且mimics组高于inhibitor组(P＜0.05);OCT4B1 mRNA和蛋白水平、细胞穿膜数、细胞存活率、单克隆形成数mimics组降低,inhibitor组升高,且mimics组低于inhibitor组(P＜0.05)。 结论miR-299-3p过表达可抑制结直肠癌细胞SW480增殖、迁移、侵袭,促进其凋亡,可能与miR-299-3p抑制OCT4B1 mRNA和蛋白表达有关。     

Physiologically Based Pharmacokinetic Modeling in Regulatory Science: An Update From the U.S. Food and Drug Administration’s Office of Clinical Pharmacology

This commentary provides an update on the status of physiologically based pharmacokinetic modeling and simulation at the U.S. Food and Drug Administration's Office of Clinical Pharmacology. Limitations and knowledge gaps in integration of physiologically based pharmacokinetic approach to inform regulatory decision making, as well as the importance of scientific engagement with drug developers who intend to use this approach, are highlighted.