Publications by authors named "Kehan Zhang"

25 Publications

  • Page 1 of 1

RNA-responsive elements for eukaryotic translational control.

Nat Biotechnol 2021 Oct 28. Epub 2021 Oct 28.

Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, USA.

The ability to control translation of endogenous or exogenous RNAs in eukaryotic cells would facilitate a variety of biotechnological applications. Current strategies are limited by low fold changes in transgene output and the size of trigger RNAs (trRNAs). Here we introduce eukaryotic toehold switches (eToeholds) as modular riboregulators. eToeholds contain internal ribosome entry site sequences and form inhibitory loops in the absence of a specific trRNA. When the trRNA is present, eToeholds anneal to it, disrupting the inhibitory loops and allowing translation. Through optimization of RNA annealing, we achieved up to 16-fold induction of transgene expression in mammalian cells. We demonstrate that eToeholds can discriminate among viral infection status, presence or absence of gene expression and cell types based on the presence of exogenous or endogenous RNA transcripts.
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http://dx.doi.org/10.1038/s41587-021-01068-2DOI Listing
October 2021

Association of Retail Environment and Neighborhood Socioeconomic Status with Mortality among Community-dwelling Older Adults in the US: Cardiovascular Health Study.

J Gerontol A Biol Sci Med Sci 2021 Oct 20. Epub 2021 Oct 20.

Global Health Research Center, Duke Kunshan University, Kunshan, Jiangsu, China.

Background: Few studies have examined the association of neighborhood environment and mortality among community-dwelling older populations. Geographic Information Systems (GIS)-based measures of neighborhood physical environment may provide new insights on the health effects of the social and built environment.

Methods: We studied 4,379 community-dwelling older adults in the US aged ≥65 years from the Cardiovascular Health Study. Principal component analysis was used to identify neighborhood components from 48 variables assessing facilities and establishments, demographic composition, socio-economic status, and economic prosperity. We used a Cox model to evaluate the association of neighborhood components with five-year mortality. Age, sex, race, education, income, marital status, body mass index, smoking status, disability, coronary heart disease, and diabetes were included as covariates. We also examined the interactions between neighborhood components and sex and race (Black vs. white or other).

Results: We identified five neighborhood components, representing facilities and resources, immigrant communities, community-level economic deprivation, resident-level socio-economic status and residents' age. Communities' economic deprivation and residents' socio-economic status were significantly associated with five-year mortality. We did not find interactions between sex or race and any of the five neighborhood components. The results were similar in a sensitivity analysis where we used ten-year mortality as the outcome.

Conclusions: We found that communities' economic status but not facilities in communities was associated with mortality among older adults. These findings revealed the importance and benefits living in a socio-economically advantaged neighborhood could have on health among older residents with different demographic backgrounds.
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http://dx.doi.org/10.1093/gerona/glab319DOI Listing
October 2021

Sarc-Graph: Automated segmentation, tracking, and analysis of sarcomeres in hiPSC-derived cardiomyocytes.

PLoS Comput Biol 2021 10 6;17(10):e1009443. Epub 2021 Oct 6.

Department of Mechanical Engineering, Boston University, Boston, Massachusetts, United States of America.

A better fundamental understanding of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) has the potential to advance applications ranging from drug discovery to cardiac repair. Automated quantitative analysis of beating hiPSC-CMs is an important and fast developing component of the hiPSC-CM research pipeline. Here we introduce "Sarc-Graph," a computational framework to segment, track, and analyze sarcomeres in fluorescently tagged hiPSC-CMs. Our framework includes functions to segment z-discs and sarcomeres, track z-discs and sarcomeres in beating cells, and perform automated spatiotemporal analysis and data visualization. In addition to reporting good performance for sarcomere segmentation and tracking with little to no parameter tuning and a short runtime, we introduce two novel analysis approaches. First, we construct spatial graphs where z-discs correspond to nodes and sarcomeres correspond to edges. This makes measuring the network distance between each sarcomere (i.e., the number of connecting sarcomeres separating each sarcomere pair) straightforward. Second, we treat tracked and segmented components as fiducial markers and use them to compute the approximate deformation gradient of the entire tracked population. This represents a new quantitative descriptor of hiPSC-CM function. We showcase and validate our approach with both synthetic and experimental movies of beating hiPSC-CMs. By publishing Sarc-Graph, we aim to make automated quantitative analysis of hiPSC-CM behavior more accessible to the broader research community.
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http://dx.doi.org/10.1371/journal.pcbi.1009443DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8523047PMC
October 2021

Curcumin Inhibits Replication of Human Parainfluenza Virus Type 3 by Affecting Viral Inclusion Body Formation.

Biomed Res Int 2021 9;2021:1807293. Epub 2021 Aug 9.

Pathogen Biology and Immunology Laboratory and Laboratory of Tissue and Cell Biology, Experimental Teaching and Management Center, Chongqing Medical University, Chongqing 401331, China.

Human Parainfluenza Virus Type 3 (HPIV3) is one of the main pathogens that cause acute lower respiratory tract infections in infants and young children. However, there are currently no effective antiviral drugs and vaccines. Herein, we found that a natural compound, curcumin, inhibits HPIV3 infection and has antiviral effects on entry and replication of the virus life cycle. Immunofluorescence and western blotting experiments revealed that curcumin disrupts F-actin and inhibits viral inclusion body (IB) formation, thus inhibiting virus replication. Curcumin can also downregulate cellular PI4KB and interrupt its colocalization in viral IBs. This study verified the antiviral ability of curcumin on HPIV3 infection and preliminarily elucidated its influence on viral replication, providing a theoretical basis for antiviral drug development of HPIV3 and other parainfluenza viruses.
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http://dx.doi.org/10.1155/2021/1807293DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8367592PMC
September 2021

Oxypeucedanin is a Mechanism-based Inactivator of CYP2B6 and CYP2D6.

Curr Drug Metab 2021 ;22(11):882-892

Wuya College of Innovation, Shenyang Pharmaceutical University, 103 Wenhua Road, Shenyang, Liaoning, 110016, China.

Background: Herbal medicine Angelica dahurica is widely employed for the treatment of rheumatism and pain relief in China. Oxypeucedanin is a major component in the herb.

Objectives: The objectives of this study are aimed at the investigation of mechanism-based inactivation of CYP2B6 and CYP2D6 by oxypeucedanin, characterization of the reactive metabolites associated with the enzyme inactivation, and identification of the P450s participating in the bioactivation of oxypeucedanin.

Methods: Oxypeucedanin was incubated with liver microsomes or recombinant CYPs2B6 and 2D6 under designed conditions, and the enzyme activities were measured by monitoring the generation of the corresponding products. The resulting reactive intermediates were trapped with GSH and analyzed by LC-MS/MS.

Results: Microsomal incubation with oxypeucedanin induced a time-, concentration-, and NADPH-dependent inhibition of CYPs2B6 and 2D6 with kinetic values of K/k 1.82 μM/0.07 min (CYP2B6) and 8.47 μM/0.044 min (CYP2D6), respectively. Ticlopidine and quinidine attenuated the observed time-dependent enzyme inhibitions. An epoxide and/or γ-ketoenal intermediate(s) derived from oxypeucedanin was/were trapped in microsomal incubations. CYP3A4 was the primary enzyme involved in the bioactivation of oxypeucedanin.

Conclusion: Oxypeucedanin was a mechanism-based inactivator of CYP2B6 and CYP2D6. An epoxide and/or γ- ketoenal intermediate(s) may be responsible for the inactivation of the two enzymes.
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http://dx.doi.org/10.2174/1389200222666210629114830DOI Listing
January 2021

Direct laser writing for cardiac tissue engineering: a microfluidic heart on a chip with integrated transducers.

Lab Chip 2021 05;21(9):1724-1737

Department of Mechanical Engineering, Boston University, Boston, MA 02215, USA. and Photonics Center, Boston University, Boston, MA 02215, USA and Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA and Division of Materials Science and Engineering, Boston University, Boston, Massachusetts 02215, USA and Department of Physics, Boston University, Boston, MA 02215, USA.

We have developed a microfluidic platform for engineering cardiac microtissues in highly-controlled microenvironments. The platform is fabricated using direct laser writing (DLW) lithography and soft lithography, and contains four separate devices. Each individual device houses a cardiac microtissue and is equipped with an integrated strain actuator and a force sensor. Application of external pressure waves to the platform results in controllable time-dependent forces on the microtissues. Conversely, oscillatory forces generated by the microtissues are transduced into measurable electrical outputs. We demonstrate the capabilities of this platform by studying the response of cardiac microtissues derived from human induced pluripotent stem cells (hiPSC) under prescribed mechanical loading and pacing. This platform will be used for fundamental studies and drug screening on cardiac microtissues.
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http://dx.doi.org/10.1039/d0lc01078bDOI Listing
May 2021

Subclinical Vascular Disease Burden and Premature Mortality Among Middle-aged Adults: the Atherosclerosis Risk in Communities Study.

J Gen Intern Med 2021 07 19;36(7):2048-2054. Epub 2021 Jan 19.

Division of Geriatrics, Department of Medicine, University of Mississippi Medical Center, Jackson, MS, USA.

Background: Whether high burden of subclinical vascular disease (SVD) is associated with increased premature mortality among middle-aged adults is not adequately understood. The association of midlife SVD burden with premature mortality among middle-aged adults free of clinical cardiovascular disease (CVD) could provide further insights into stratifying premature death beyond clinical CVD.

Objective: To determine whether high burden of subclinical vascular disease is associated with increased premature mortality among middle-aged adults.

Design: We leveraged data from the Atherosclerosis Risk in Communities Study.

Participants: Thirteen thousand eight hundred seventy-six community-dwelling blacks and whites aged 45-64 years from the Atherosclerosis Risk in Communities Study.

Main Measures: Each SVD measure-ankle-brachial index, carotid intima-media thickness, and electrocardiogram-was scored 0 (no abnormalities), 1 (minor abnormalities), or 2 (major abnormalities). An index was constructed as the sum of three measures, ranging from 0 (lowest burden) to 6 (highest burden). We used the Cox proportional-hazards model to determine the association of SVD burden with premature mortality (death before age 70) among persons free of clinical CVD. We then tested the difference in point estimates between SVD and clinical CVD.

Key Results: Among persons without CVD, the premature death was 1.7, 2.1, 2.5, and 3.8 per 1000 person-years among those with an SVD score of 0 (lowest burden), 1, 2, and 3-6 (highest burden), respectively. After multivariable-adjustment, highest SVD burden (score = 3-6; HR = 1.47) was significantly associated with premature death among persons initially without CVD. In the model where persons with and without CVD were included, high SVD burden (score: 3-6 vs. 0) and CVD did not have hugely different association with premature death (HR = 1.49 vs. 1.68; P = 0.32 for comparison).

Conclusions: Midlife SVD burden was associated with premature mortality and it could stratify premature death beyond clinical CVD. It is important to take SVD into account when designing interventions for reducing premature mortality.
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http://dx.doi.org/10.1007/s11606-020-06398-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8298717PMC
July 2021

Identification of the Functional Domain of HPIV3 Matrix Protein Interacting with Nucleocapsid Protein.

Biomed Res Int 2020 8;2020:2616172. Epub 2020 Dec 8.

Pathogen Biology and Immunology Laboratory, Tissue and Cell Biology Laboratory, Experimental Teaching Management Center, Chongqing Medical University, Chongqing 401331, China.

Human parainfluenza virus type 3 (HPIV3) is the main pathogen that causes respiratory infections in infants, young children, and the elderly. Currently, there are no vaccines and effective anti-infective drugs. Studying the replication and proliferation mechanism of HPIV3 is helpful for exploring the targets of anti-HPIV3 infection. Matrix protein (M) and nucleocapsid protein (N) are two key structural proteins of HPIV3 that exert important functions in HPIV3 proliferation. Herein, we aim to clarify the functional domains of M and N interaction. HPIV3 M and N expression plasmids of pCAGGS-HA-M and pCAGGS-N-Myc/Flag, M C-terminal truncation mutant plasmids of pCAGGSHA-MC120, MC170, MC190, and MC210, and M C-terminal plasmid of pCAGGS-HA-MC190 and C-terminal deletion mutant plasmid of pCAGGS-MN143-182 were constructed. By using immunoprecipitation, immunofluorescence, and virus-like particle (VLP) germination experiments, we found that N was encapsulated into M-mediated VLP through N and M interaction. Moreover, the C-terminus of the M played a key role in the interaction between M and N. The C-terminus of the M encapsulated the N into the VLP. We finally determined that the 143-182 amino acids in the M were the functional regions that encapsulated the N into the M-mediated VLP. Our findings confirmed the interaction between M and N and for the first time clarified that the 143-182 amino acid region in M was the functional region that interacted with N, which provides a molecular basis for exploring effective anti-HPIV3 targets.
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http://dx.doi.org/10.1155/2020/2616172DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7787747PMC
September 2021

Residential Proximity to Major Roadways and Prevalent Hypertension Among Older Women and Men: Results From the Chinese Longitudinal Healthy Longevity Survey.

Front Cardiovasc Med 2020 17;7:587222. Epub 2020 Nov 17.

Center for Healthy Aging and Development Studies, National School of Development, Peking University, Beijing, China.

Prior studies suggested that residential proximity to major roadways was associated with increased risks of cardiovascular diseases in developed countries, for which one explanation is that road proximity could heighten the risks of hypertension. However, the association of residential distance to major roadways with hypertension is still unclear in low- and middle-income countries (LMICs) with levels of air pollution and socioeconomic development distinctively different from developed countries. We derived data from the eighth wave of the Chinese Longitudinal Healthy Longevity Survey, a nationwide prospective cohort. The present study included 12,881 individuals older than 65 years (mean age, 85.2 ± 11.7 years) with 55.8% of them being female. We ascertained the residential proximity to major roadways based on self-reports and hypertension was defined as systolic blood pressure ≥140 mm Hg or diastolic blood pressure ≥90 mm Hg. We then used logistic regression to examine the association between residential distance to major roadways and hypertension. The odds ratios (ORs) of hypertension for participants living 50 to 100, 101 to 200, and ≥200 meters from major roads were 1.17 [95% confidence interval (95% CI) = 1.02-1.33], 1.21 (95% CI = 1.05-1.41), and 1.22 (95% CI = 1.10-1.34), respectively, compared to those living within 50 m ( < 0.001). Significant effects of modifications from socioeconomic status and accessibility to health care resources were observed (s for interaction < 0.05). Compared to living within 50 m from a major roadway, the ORs of hypertension for living ≥50 m were higher in manual/agricultural workers, low-education groups, participants without household ventilation, and participants lacking in health education and health care resources. We observed considerable variations across geographic regions with the association in question attenuating in Eastern China but remaining significant in other regions. Residential proximity to major roadways was associated with lower odds of hypertension among older adults in China. The utility of residential proximity to major roadways as a marker of increased risks of hypertension and cardiovascular diseases may need to be revisited in LMICs.
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http://dx.doi.org/10.3389/fcvm.2020.587222DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7705226PMC
November 2020

Distinct effects of different matrix proteoglycans on collagen fibrillogenesis and cell-mediated collagen reorganization.

Sci Rep 2020 11 4;10(1):19065. Epub 2020 Nov 4.

Bioengineering Graduate Group, University of Pennsylvania, Philadelphia, PA, 19104, USA.

The extracellular matrix (ECM) is a complex mixture composed of fibrillar collagens as well as additional protein and carbohydrate components. Proteoglycans (PGs) contribute to the heterogeneity of the ECM and play an important role in its structure and function. While the small leucine rich proteoglycans (SLRPs), including decorin and lumican, have been studied extensively as mediators of collagen fibrillogenesis and organization, the function of large matrix PGs in collagen matrices is less well known. In this study, we showed that different matrix PGs have distinct roles in regulating collagen behaviors. We found that versican, a large chondroitin sulfate PG, promotes collagen fibrillogenesis in a turbidity assay and upregulates cell-mediated collagen compaction and reorganization, whereas aggrecan, a structurally-similar large PG, has different and often opposing effects on collagen. Compared to versican, decorin and lumican also have distinct functions in regulating collagen behaviors. The different ways in which matrix PGs interact with collagen have important implications for understanding the role of the ECM in diseases such as fibrosis and cancer, and suggest that matrix PGs are potential therapeutic targets.
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http://dx.doi.org/10.1038/s41598-020-76107-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7642422PMC
November 2020

Synthesis, bioconversion, pharmacokinetic and pharmacodynamic evaluation of N-isopropyl-oxy-carbonyloxymethyl prodrugs of CZh-226, a potent and selective PAK4 inhibitor.

Eur J Med Chem 2020 Jan 14;186:111878. Epub 2019 Nov 14.

Key Laboratory of Structure-Based Drug Design & Discovery of Ministry of Education, Shenyang Pharmaceutical University, Shenyang, 110016, China. Electronic address:

We have previously disclosed compound 3 (CZh-226), a potent and selective PAK4 inhibitor, but its development was delayed due to poor oral pharmacokinetics. In an attempt to improve this issue, we synthesised a series of prodrugs by masking its terminal nitrogen of the piperazine moiety. Most synthesised prodrugs of 3 have low or no inhibition of PAK4 activity. The stability of synthetic prodrugs was evaluated in PBS, SGF, SIF, rat plasma and liver S9 fraction. Of these, prodrug 19 was not only stable under both acidic and neutral conditions but also could be quickly converted to parent drug 3 in rat plasma and liver S9 fraction. Such effective conversion into parent drug 3 was observed in rats, providing higher exposure of 3 compared to its direct administration. When given via oral route at daily doses of 25 and 50 mg/kg, the prodrug 19 was effective and well tolerated in mouse model of HCT-116 and B16F10.
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http://dx.doi.org/10.1016/j.ejmech.2019.111878DOI Listing
January 2020

Piperine Is a Mechanism-Based Inactivator of CYP3A.

Drug Metab Dispos 2020 02 20;48(2):123-134. Epub 2019 Nov 20.

State Key Laboratory of Functions and Applications of Medicinal Plants, Key Laboratory of Pharmaceutics of Guizhou Province, and Key Laboratory of Environmental Pollution Monitoring and Disease Control, Ministry of Education, Guizhou Medical University, Guiyang, P. R. China(J.Z.); Wuya College of Innovation, Shenyang Pharmaceutical University, Shenyang, Liaoning, P. R. China(T.C., Q.W., X.T., K.Z., Y.P., J.Z.)

Piperine (PPR) is the representative alkaloid component of the piper species (family: Piperaceae). Our rapid screening study found PPR caused time-dependent inhibition of cytochrome P450s (CYP) 3A and 2D6, and CYP3A was inactivated the most. Further study demonstrated that PPR is a time-, concentration-, and NADPH-dependent inhibitor of CYP3A, and significant loss (49.5% ± 3.9%) of CYP3A activity was observed after 20minute incubations with 80 M PPR at 37°C. The values of and were 30.7 M and 0.041 minutes, respectively. CYP3A competitive inhibitor ketoconazole showed protective effect against the enzyme inactivation. Superoxide dismutase/catalase and GSH displayed minor protection against the PPR-caused enzyme inactivation. Ferricyanide partially reduced the enzyme inhibition by PPR. Additionally, NADPH-dependent formation of reactive metabolites from PPR were found in human liver microsomal incubation mixtures. An -quinone intermediate was trapped by NAC in microsomal incubations with PPR. DM-PPR, demethylene metabolite of PPR, showed weak enzyme inactivation relative to that caused by PPR. It appears that both carbene and -quinone intermediates were involved in the inactivation of CYP3A caused by PPR. SIGNIFICANCE STATEMENT: CYP3A subfamily members (mainly CYP3A4 and CYP3A5) play a critical role in drug metabolism. Piperine (PPR), a methylenedioxyphenyl derivative combined with an unsaturated ketone, is the major active ingredient of pepper. PPR revealed time-, concentration-, and NADPH-dependent inhibitory effect on CYP3A. Carbene and quinone metabolites were both involved in the observed CYP3A inactivation by PPR. Apparently, the unsaturated ketone moiety did not participate in the enzyme inactivation. The present study sounds an alert of potential risk for food-drug interactions.
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http://dx.doi.org/10.1124/dmd.119.088955DOI Listing
February 2020

Mesenchymal Stem Cells and their Exosomes: Promising Therapeutics for Chronic Pain.

Curr Stem Cell Res Ther 2019 ;14(8):644-653

Department of Anesthesiology, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China.

Chronic pain is a common condition that seriously affects the quality of human life with variable etiology and complicated symptoms; people who suffer from chronic pain may experience anxiety, depression, insomnia, and other harmful emotions. Currently, chronic pain treatments are nonsteroidal anti-inflammatory drugs and opioids; these drugs are demonstrated to be insufficient and cause severe side effects. Therefore, research into new therapeutic strategies for chronic pain is a top priority. In recent years, stem cell transplantation has been demonstrated to be a potent alternative for the treatment of chronic pain. Mesenchymal stem cells (MSCs), a type of pluripotent stem cell, exhibit multi-directional differentiation, promotion of stem cell implantation, and immune regulation; they have also been shown to exert analgesic effects in several chronic pain models. Exosomes produced by MSCs have been demonstrated to relieve painful symptoms with fewer side effects. In this review, we summarize the therapeutic use of MSCs in various chronic pain studies. We also discuss ways to enhance the treatment effect of MSCs. We predict in the future, cell-free therapies for chronic pain will develop from exosomes secreted by MSCs.
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http://dx.doi.org/10.2174/1574888X14666190912162504DOI Listing
April 2020

Cytochrome P450 mediated metabolic activation of chrysophanol.

Chem Biol Interact 2018 Jun 24;289:57-67. Epub 2018 Apr 24.

Wuya College of Innovation, Shenyang Pharmaceutical University, Shenyang, Liaoning, 110016, PR China(1); State Key Laboratory of Functions and Applications of Medicinal Plants, Key Laboratory of Pharmaceutics of Guizhou Province, Guizhou Medical University, Guiyang, Guizhou, 550025, PR China(1). Electronic address:

Chrysophanol, a major anthraquinone component occurring in many traditional Chinese herbs, is accepted as important active component with various pharmacological actions such as antibacterial and anticancer activity. Previous studies demonstrated that exposure to chrysophanol induced cytotoxicity, but the mechanisms of the toxic effects remain unknown. In the present metabolism study, three oxidative metabolites (M1-M3, aloe-emodine, 7-hydroxychrysophanol, and 2-hydroxychrysophanol) and five GSH conjugates (M4-M8) were detected in rat and human liver microsomal incubations of chrysophanol supplemented with GSH, and the formation of the metabolites was NADPH dependent except M4 and M5. M4 and M5 were directly derived from parent compound chrysophanol, M6 arose from M2, and M7 and M8 resulted from the oxidation of M4 and M5. Metabolites M5 and M6 were also observed in bile of rats after exposure to chrysophanol, M1-M3 and one NAC conjugate (M9) were detected in urine of rats administrated chrysophanol, and urinary metabolite M9 originated from the degradation of biliary GSH conjugation M6. Recombinant P450 enzyme incubation and microsome inhibition studies demonstrated that P450 1A2 was the primary enzyme responsible for the metabolic activation of chrysophanol and that P450 2B6 and P450 3A4 also participated in the generation of the oxidative metabolites. These findings helped us to understand the mechanisms of chrysophanol-induced cytotoxicity.
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http://dx.doi.org/10.1016/j.cbi.2018.04.015DOI Listing
June 2018

Force Generation via β-Cardiac Myosin, Titin, and α-Actinin Drives Cardiac Sarcomere Assembly from Cell-Matrix Adhesions.

Dev Cell 2018 01 8;44(1):87-96.e5. Epub 2018 Jan 8.

Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA; The Wyss Institute for Biologically Inspired Engineering at Harvard University, Boston, MA 02115, USA. Electronic address:

Truncating mutations in the sarcomere protein titin cause dilated cardiomyopathy due to sarcomere insufficiency. However, it remains mechanistically unclear how these mutations decrease sarcomere content in cardiomyocytes. Utilizing human induced pluripotent stem cell-derived cardiomyocytes, CRISPR/Cas9, and live microscopy, we characterize the fundamental mechanisms of human cardiac sarcomere formation. We observe that sarcomerogenesis initiates at protocostameres, sites of cell-extracellular matrix adhesion, where nucleation and centripetal assembly of α-actinin-2-containing fibers provide a template for the fusion of Z-disk precursors, Z bodies, and subsequent striation. We identify that β-cardiac myosin-titin-protocostamere form an essential mechanical connection that transmits forces required to direct α-actinin-2 centripetal fiber assembly and sarcomere formation. Titin propagates diastolic traction stresses from β-cardiac myosin, but not α-cardiac myosin or non-muscle myosin II, to protocostameres during sarcomerogenesis. Ablating protocostameres or decoupling titin from protocostameres abolishes sarcomere assembly. Together these results identify the mechanical and molecular components critical for human cardiac sarcomerogenesis.
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http://dx.doi.org/10.1016/j.devcel.2017.12.012DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6421364PMC
January 2018

Fast and non-invasive serum detection technology based on surface-enhanced Raman spectroscopy and multivariate statistical analysis for liver disease.

Nanomedicine 2018 02 29;14(2):451-459. Epub 2017 Nov 29.

Beijing Institute of Radiation Medicine, Beijing, PR China. Electronic address:

This study explored a rapid and nondestructive liver disease detection technique based on surface-enhanced Raman spectroscopy (SERS) to realize the early diagnosis, prevention, and treatment of liver disease. SERS signals of serum were obtained from 304 normal individuals, 333 patients with hepatopathy, and 99 patients with esophageal cancer. The Raman spectra of different diseases were compared and diagnostic models of liver disease were established using orthogonal partial least squares discriminant analysis (OPLS-DA). The classification efficiencies of the different models were comprehensively evaluated through the receiver operating characteristic (ROC) curve and ten-fold cross validation. Area under the ROC curve is of greater than 0.97, indicating excellent classification of the groups. The accuracy rate of the test set reached 95.33%, and the lowest was 81.76% using the ten-fold cross validation. Thus, OPLS-DA combined with serum SERS is a rapid and non-invasive technique for the diagnosis of liver disease.
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http://dx.doi.org/10.1016/j.nano.2017.11.022DOI Listing
February 2018

Vancomycin-modified [email protected]@Ag microflowers as effective antimicrobial agents.

Int J Nanomedicine 2017 13;12:3077-3094. Epub 2017 Apr 13.

College of Life Sciences & Bio-Engineering, Beijing University of Technology.

Nanomaterials combined with antibiotics exhibit synergistic effects and have gained increasing interest as promising antimicrobial agents. In this study, vancomycin-modified magnetic-based silver microflowers (Van/[email protected]@Ag microflowers) were rationally designed and prepared to achieve strong bactericidal ability, a wide antimicrobial spectrum, and good recyclability. High-performance [email protected]@Ag microflowers served as a multifunction-supporting matrix and exhibited sufficient magnetic response property due to their 200 nm FeO core. The microflowers also possessed a highly branched flower-like Ag shell that provided a large surface area for effective Ag ion release and bacterial contact. The modified-vancomycin layer was effectively bound to the cell wall of bacteria to increase the permeability of the cell membrane and facilitate the entry of the Ag ions into the bacterium, resulting in cell death. As such, the fabricated Van/[email protected]@Ag microflowers were predicted to be an effective and environment-friendly antibacterial agent. This hypothesis was verified through sterilization of Gram-negative and Gram-positive methicillin-resistant , with minimum inhibitory concentrations of 10 and 20 μg mL, respectively. The microflowers also showed enhanced effect compared with bare [email protected]@Ag microflowers and free-form vancomycin, confirming the synergistic effects of the combination of the two components. Moreover, the antimicrobial effect was maintained at more than 90% after five cycling assays, indicating the high stability of the product. These findings reveal that Van/[email protected]@Ag microflowers exhibit promising applications in the antibacterial fields.
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http://dx.doi.org/10.2147/IJN.S132570DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5399987PMC
September 2017

Integrative Analysis of PRKAG2 Cardiomyopathy iPS and Microtissue Models Identifies AMPK as a Regulator of Metabolism, Survival, and Fibrosis.

Cell Rep 2016 12;17(12):3292-3304

Department of Genetics, Harvard Medical School, Boston, MA 02115, USA; Division of Cardiovascular Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA; Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA. Electronic address:

AMP-activated protein kinase (AMPK) is a metabolic enzyme that can be activated by nutrient stress or genetic mutations. Missense mutations in the regulatory subunit, PRKAG2, activate AMPK and cause left ventricular hypertrophy, glycogen accumulation, and ventricular pre-excitation. Using human iPS cell models combined with three-dimensional cardiac microtissues, we show that activating PRKAG2 mutations increase microtissue twitch force by enhancing myocyte survival. Integrating RNA sequencing with metabolomics, PRKAG2 mutations that activate AMPK remodeled global metabolism by regulating RNA transcripts to favor glycogen storage and oxidative metabolism instead of glycolysis. As in patients with PRKAG2 cardiomyopathy, iPS cell and mouse models are protected from cardiac fibrosis, and we define a crosstalk between AMPK and post-transcriptional regulation of TGFβ isoform signaling that has implications in fibrotic forms of cardiomyopathy. Our results establish critical connections among metabolic sensing, myocyte survival, and TGFβ signaling.
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http://dx.doi.org/10.1016/j.celrep.2016.11.066DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5193246PMC
December 2016

A rapid SERS method for label-free bacteria detection using polyethylenimine-modified Au-coated magnetic microspheres and [email protected] nanoparticles.

Analyst 2016 Oct;141(22):6226-6238

College of Life Sciences & Bio-Engineering, Beijing University of Technology, Beijing 100124, PR China. and Beijing Institute of Radiation Medicine, Beijing 100850, PR China. and Henan University of Chinese Medicine, Zhengzhou, Henan 450008, PR China.

A rapid, sensitive, and label-free SERS detection method for bacteria pathogens is reported for the first time. The method, which is based on the combination of polyethylenimine (PEI)-modified Au-coated magnetic microspheres ([email protected]@PEI) and concentrated [email protected] nanoparticles (NPs), was named the capture-enrichment-enhancement (CEE) three-step method. A novel [email protected] microsphere with monodispersity and strong magnetic responsiveness was synthesized as a magnetic SERS substrate and amino functionalized by PEI self-assembly. The negatively charged bacteria were quickly captured and enriched by the positively charged [email protected]@PEI microspheres, and the bacteria SERS signal was synergistically enhanced by using [email protected]@PEI microspheres and [email protected] NPs in conjunction. The CEE three-step method proved useful in tap water and milk samples, and the total assay time required was only 10 min. Results further demonstrated that the CEE three-step method could be a common approach for detecting a wide range of bacteria, as verified by its detection of the Gram-positive bacterium E. coli and Gram-positive bacterium S. aureus at a detection limit of as low as 10 cells per mL. Therefore, our CEE three-step method offered the significant advantages of short assay time, simple operating procedure, and higher sensitivity than previously reported methods of SERS-based bacteria detection.
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http://dx.doi.org/10.1039/c6an01105eDOI Listing
October 2016

Magnetically enhanced cell delivery for accelerating recovery of the endothelium in injured arteries.

J Control Release 2016 Jan 17;222:169-75. Epub 2015 Dec 17.

Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA. Electronic address:

Arterial injury and disruption of the endothelial layer are an inevitable consequence of interventional procedures used for treating obstructive vascular disease. The slow and often incomplete endothelium regrowth after injury is the primary cause of serious short- and long-term complications, including thrombosis, restenosis and neoatherosclerosis. Rapid endothelium restoration has the potential to prevent these sequelae, providing a rationale for developing strategies aimed at accelerating the reendothelialization process. The present studies focused on magnetically guided delivery of endothelial cells (EC) functionalized with biodegradable magnetic nanoparticles (MNP) as an experimental approach for achieving rapid and stable cell homing and expansion in stented arteries. EC laden with polylactide-based MNP exhibited strong magnetic responsiveness, capacity for cryopreservation and rapid expansion, and the ability to disintegrate internalized MNP in both proliferating and contact-inhibited states. Intracellular decomposition of BODIPY558/568-labeled MNP monitored non-invasively based on assembly state-dependent changes in the emission spectrum demonstrated cell proliferation rate-dependent kinetics (average disassembly rates: 6.6±0.8% and 3.6±0.4% per day in dividing and contact-inhibited EC, respectively). With magnetic guidance using a transient exposure to a uniform 1-kOe field, stable localization and subsequent propagation of MNP-functionalized EC, markedly enhanced in comparison to non-magnetic delivery conditions, were observed in stented rat carotid arteries. In conclusion, magnetically guided delivery is a promising experimental strategy for accelerating endothelial cell repopulation of stented blood vessels after angioplasty.
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http://dx.doi.org/10.1016/j.jconrel.2015.12.025DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4718792PMC
January 2016

Nanoparticle-mediated delivery of a rapidly activatable prodrug of SN-38 for neuroblastoma therapy.

Biomaterials 2015 May 16;51:22-29. Epub 2015 Feb 16.

Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA. Electronic address:

Nanomedicine-based strategies have the potential to improve therapeutic performance of a wide range of anticancer agents. However, the successful implementation of nanoparticulate delivery systems requires the development of adequately sized nanocarriers delivering their therapeutic cargo to the target in a protected, pharmacologically active form. The present studies focused on a novel nanocarrier-based formulation strategy for SN-38, a topoisomerase I inhibitor with proven anticancer potential, whose clinical application is compromised by toxicity, poor stability and incompatibility with conventional delivery vehicles. SN-38 encapsulated in biodegradable sub-100 nm sized nanoparticles (NP) in the form of its rapidly activatable prodrug derivative with tocopherol succinate potently inhibited the growth of neuroblastoma cells in a dose- and exposure time-dependent manner, exhibiting a delayed response pattern distinct from that of free SN-38. In a xenograft model of neuroblastoma, prodrug-loaded NP caused rapid regression of established large tumors, significantly delayed tumor regrowth after treatment cessation and markedly extended animal survival. The NP formulation strategy enabled by a reversible chemical modification of the drug molecule offers a viable means for SN-38 delivery achieving sustained intratumoral drug levels and contributing to the potency and extended duration of antitumor activity, both prerequisites for effective treatment of neuroblastoma and other cancers.
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http://dx.doi.org/10.1016/j.biomaterials.2015.01.075DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4361798PMC
May 2015

Real-time analysis of composite magnetic nanoparticle disassembly in vascular cells and biomimetic media.

Proc Natl Acad Sci U S A 2014 Mar 3;111(11):4245-50. Epub 2014 Mar 3.

Division of Cardiology Research, The Children's Hospital of Philadelphia, Philadelphia, PA 19104.

The fate of nanoparticle (NP) formulations in the multifaceted biological environment is a key determinant of their biocompatibility and therapeutic performance. An understanding of the degradation patterns of different types of clinically used and experimental NP formulations is currently incomplete, posing an unmet need for novel analytical tools providing unbiased quantitative measurements of NP disassembly directly in the medium of interest and in conditions relevant to specific therapeutic/diagnostic applications. In the present study, this challenge was addressed with an approach enabling real-time in situ monitoring of the integrity status of NPs in cells and biomimetic media using Förster resonance energy transfer (FRET). Disassembly of polylactide-based magnetic NPs (MNPs) was investigated in a range of model biomimetic media and in cultured vascular cells using an experimentally established quantitative correlation between particle integrity and FRET efficiency controlled through adjustments in the spectral overlap between two custom-synthesized polylactide-fluorophore (boron dipyrromethene) conjugates incorporated in MNPs. The results suggest particle disassembly governed by diffusion-reaction processes with kinetics strongly dependent on conditions promoting release of oligomeric fragments from the particle matrix. Thus, incubation in gels simulating the extracellular environment and in protein-rich serum resulted in notably lower and higher MNP decomposition rates, respectively, compared with nonviscous liquid buffers. The diffusion-reaction mechanism also is consistent with a significant cell growth-dependent acceleration of MNP processing in dividing vs. contact-inhibited vascular cells. The FRET-based analytical strategy and experimental results reported herein may facilitate the development and inform optimization of biodegradable nanocarriers for cell and drug delivery applications.
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http://dx.doi.org/10.1073/pnas.1324104111DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3964081PMC
March 2014
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