A large percentage of drugs fail in clinical studies due to cardiac toxicity; thus, development of sensitive in vitro assays that can evaluate potential adverse effects on cardiomyocytes is extremely important for drug development. Human cardiomyocytes derived from stem cell sources offer more clinically relevant cell-based models than those presently available. Human-induced pluripotent stem cell-derived cardiomyocytes are especially attractive because they express ion channels and demonstrate spontaneous mechanical and electrical activity similar to adult cardiomyocytes. Here we demonstrate techniques for measuring the impact of pharmacologic compounds on the beating rate of cardiomyocytes with ImageXpress Micro and FLIPR Tetra systems. The assays employ calcium-sensitive dyes to monitor changes in Ca 2+ fluxes synchronous with cell beating, which allows monitoring of the beat rate, amplitude, and other parameters. We demonstrate here that the system is able to detect concentration-dependent atypical patterns caused by hERG inhibitors and other ion channel blockers. We also show that both positive and negative chronotropic effects on cardiac rate can be observed and IC 50 values determined. This methodology is well suited for safety testing and can be used to estimate efficacy and dosing of drug candidates prior to clinical studies.

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17β-Estradiol (E2) regulates transcriptional activity partly by inducing protein-kinase cascades, leading to the phosphorylation of estrogen receptors (ERs) and other functional proteins. Many of these phosphorylation events are also modulated by growth factors. To gain an insight into E2-modulated protein phosphorylation, we applied quantitative phosphoproteomics to investigate global changes in protein phosphorylation induced by E2 in MCF-7 cells. Proteomic analyses using stable isotope dimethyl labeling coupled with immobilized metal affinity chromatography-hydrophilic interaction liquid chromatography (IMAC-HILIC) fractionation and nanoLC-MS/MS identified and quantified 2857 unique phosphorylation sites in 1338 phosphoproteins from 1 mg of total cellular protein. In addition to S118 of ERα, a 30-min E2 treatment significantly altered the status of 403 phosphorylation sites, including 112 novel sites. Interestingly, the substrate motifs for ERK1/2 were largely enriched in both the up-regulated and down-regulated phosphorylation sites. An increase in the phosphorylation on either the T202 or Y204 sites of ERK1 was observed after E2 treatment, while dual phosphorylation on both sites were not detected, implying that a feedback loop to deactivate MAPK signaling was achieved during a 30-min E2 treatment. In contrast, the PKA and CKII substrate motifs were majorly enriched among the up-regulated phosphorylation sites. Western blot analysis confirmed that E2 increased the phosphorylation level of S226 within a CKII motif of HSP90β by a factor of 2- to 3-fold without changing the total protein expression level. E2 also up-regulated phosphorylations of S255 in HSP90β and S353 within a CKII motif of HSP90α. These results indicated that E2 may modulate gene transcription by affecting the stability, function, and activity of many regulators through a HSP90 phosphorylation-mediated chaperoning process. This study, using a quantitative, multidimensional separation phosphoproteomic approach that required a relatively low amount of cells, provides new insights into the diversity, variability, and dynamic nature of the protein phosphorylation/dephosphorylation elicited by E2.

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BackgroundProcedure sedation and analgesia (PSA) is often used to alleviate discomfort and to facilitate fracture reduction for patients with distal radius fracture in emergency departments and clinics, but risks of respiratory distress and needs for different levels of monitoring under PSA are still under concern. Hematoma block (HB) is a simple alternative method of providing rapid pain relief during reduction of distal radius fracture. However, there is still in lack of strong evidence to promote HB over PSA in clinical practice. The aim of this study was to compare HB and PSA for adult and pediatric patients during reduction of displaced distal radius fracture to identify the level of pain relief, frequency of adverse effects (AEs), and reduction failure.MethodsThe PubMed, ScienceDirect, Cochrane Library, and ClinicalTrials.gov were searched for studies comparing HB or PSA in distal radius fracture reduction. The search revealed four randomized controlled trials and one non-randomized trial, which included two studies of pediatric subjects and three studies of adult subjects. Subgroup meta-analysis for adult and pediatric groups were specifically performed according to age difference to avoid potential bias.ResultsIn the adult group, the effect of HB on post-reduction pain severity was better than that of PSA with significant heterogeneity (Hedges’ g − 0.600, 95% confidence interval (CI) − 1.170 to − 0.029, p = 0.039), although there was no difference on the pain severity during reduction between these two groups with significant heterogeneity (Hedges’ g 0.356, 95% CI − 1.101 to 1.812, p = 0.632). In the pediatric group, the treatment effect on pain severity was significantly better by HB than that by PSA but without significant heterogeneity (Hedges’ g − 0.402, 95% CI − 0.718 to − 0.085, p = 0.013, I2 < 0.001%). Most of the reported adverse effects (AEs) include nausea, vomiting, and respiratory distress developed in adult patients treated by PSA. The rates of reported AEs did not significantly differ between HB and PSA in the pediatric group. Additionally, final outcomes of reduction failure did not significantly differ between HB and PSA in both adult and pediatric groups.ConclusionHematoma block is a safe and effective alternative of anesthesia in reduction of distal radius fracture without inferior pain relief compared with PSA among adult and pediatric patients.Electronic supplementary materialThe online version of this article (10.1186/s13018-018-0772-7) contains supplementary material, which is available to authorized users.