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A portable device for studying the effects of fluid flow on degradation properties of biomaterials inside cell incubators

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Regenerative Biomaterials 2019年第1期6卷 39-48页

作者： Wensen Jiang Jiajia Lin Alex H.Chen Jianwei Pan Huinan Liu Department of Bioengineering Materials Science and Engineering ProgramStem Cell Center Department of Mechanical Engineering University of CaliforniaRiversideRiversideCA 92521USA Department of Bioengineering University of CaliforniaRiversideRiversideCA 92521USA Department of Neurosurgery The First Affiliated Hospital of Zhejiang UniversityHangzhou 310003China

A portable device was designed and constructed for studying the properties of biomaterials in physiologically relevant fluids under controllable flow conditions that closely simulate fluid flow inside the *** device can fit entirely inside a cell incubator;and,thus,it can be used directly under standard cell culture *** impedance-driven pump was built in the sterile flow loop to control the flow rates of fluids,which made the device small and portable for easy deployment in the *** demonstrate the device functions,magnesium(Mg)as a representative biodegradable material was tested in the flow device for immersion degradation under flow versus static conditions,while the flow module was placed inside a standard cell *** flow rate was controlled at 0.1760.06 ml/s for this study;and,the flow rate is adjustable through the controller module outside of incubators for simulating the flow rates in the ranges of blood flow in human artery(0.050.43 ml/s)and vein(0.020.08 ml/s).Degradation of Mg under flow versus static conditions was characterized by measuring the changes of sample mass and thickness,and Mg2t ion concentrations in the immersion *** chemistry and morphology of Mg after immersion under flow versus static conditions were *** portable impedance-driven flow device is easy to fit inside an incubator and much smaller than a peristaltic pump,providing a valuable solution for studying biomaterials and implants(*** or ureteral stents)in body fluids under flow versus static conditions with or without cells.

关键词： portable flow device impedance-driven pump biomaterials body fluids magnesium(Mg)degradation

On the Volume Conservation of the Immersed Boundary Method

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Communications in Computational Physics 2012年第7期12卷 401-432页

作者： Boyce E.Griffith Leon H.Charney Division of Cardiology New York University School of Medicine550 First AvenueNew YorkNew York 10016USA

The immersed boundary(IB)method is an approach to problems of fluid-structure interaction in which an elastic structure is immersed in a viscous incompressible *** IB formulation of such problems uses a Lagrangian description of the structure and an Eulerian description of the *** is well known that some versions of the IB method can suffer from poor volume *** have been introduced to improve the volume-conservation properties of the IB method,but they either have been fairly specialized,or have used complex,nonstandard Eulerian finite-difference *** this paper,we use quasi-static and dynamic benchmark problems to investigate the effect of the choice of Eulerian discretization on the volume-conservation properties of a formally second-order accurate IB *** consider both collocated and staggered-grid discretization *** the tests considered herein,the staggered-grid IB scheme generally yields at least a modest improvement in volume conservation when compared to cell-centered methods,and in many cases considered in this work,the spurious volume changes exhibited by the staggered-grid IB method are more than an order of magnitude smaller than those of the collocated *** also compare the performance of cell-centered schemes that use either exact or approximate projection *** find that the volumeconservation properties of approximate projection IB methods depend strongly on the formulation of the projection *** used with the IB method,we find that pressure-free approximate projection methods can yield extremely poor volume conservation,whereas pressure-increment approximate projection methods yield volume conservation that is nearly identical to that of a cell-centered exact projection method.

关键词： Immersed boundary method fluid-structure interaction collocated discretization staggered-grid discretization exact projection method approximate projection method volume conservation

Overactivation of histone deacetylases and EZH2 in Wilms tumorigenesis

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Genes & Diseases 2023年第5期10卷 1783-1786页

作者： Chao-Hui Chen Nguyen Yen Nhi Ngo Alun Wang Samir El-Dahr Hongbing Liu Department of Pediatrics Tulane University School of MedicineNew OrleansLA 70112USA Department of Pathology and Laboratory Medicine Tulane University School of MedicineNew OrleansLA 70112USA

Wilms tumor (WT) is the most common childhood kidney cancer. Although WT is largely curable, current treatments fail in up to 15 percent of patients. Moreover, survivors suffer from the complications and late effects of the aggressive treatments. Thus, there is a critical need to improve our understanding of tumorigenesis to develop novel therapies to reduce the treatment burden while maintaining excellent survival rates. WT is believed to arise from the immature kidney cells, nephron progenitor cells (NPCs), which have failed to differentiate properly. Previous studies revealed that Wilms cells share a transcriptional and epigenetic landscape with normal renal stem cells.1 Although several studies have shown the positive associations between WT in children and embryonic exposure to adverse environments, the underlying mechanisms remain unknown. Altered epigenetics is central to oncogenesis in many pediatric cancers. The critical contribution of epigenetic dysregulation to pediatric tumors provides a compelling rationale for the therapeutic potential of epigenetic drugs. Histone deacetylases (HDACs) and Enhancer of Zeste Homolog 2 (EZH2, a histone H3K27 methyltransferase), have been demonstrated to play a critical role in self-renewal and differentiation of mouse NPCs.2,3 In addition, altered expression and mutations of HDACs and EZH2 have been linked to many human cancers, including WT. Thus, they are among the most promising therapeutic targets for cancer treatment. We reasoned that WT would result from the unrestrained proliferation of progenitor cells due to overactive HDAC1/2 (HDAC1 and HDAC2), and EZH2. We tested this hypothesis by analyzing a clinical specimen received from the left kidney tumor of an 11-year-old male patient diagnosed with WT and four other human WT specimens. We have the approval from Tulane Human Research Protection Office & Institutional Review Boards (Study number: 2019–623) to study WT specimens. The tumor (9.5 cm × 8 cm × 7.5 cm) is cl

关键词： EZH2 Figure approval

association between stress hyperglycemia ratio and in-hospital outcomes:findings from the improving Care for Cardiovascular Disease in China-Acute Coronary Syndrome(CCC-ACS)Project

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Journal of Geriatric Cardiology 2024年第6期21卷 658-668页

作者： Wen-Jie WANG Ke-Xin WANG Jia-Long NIU Yi-Xuan LIU Hai-Long GE Hua SHEN On behalf of CCC-ACS investigators Department of Cardiology Beijing Anzhen HospitalCapital Medical UniversityBeijingChina

BACKGROUND Stress hyperglycemia ratio(SHR)could provide accurate information on the acute status of *** relationship between SHR and acute coronary syndrome(ACS)prognosis remains *** study was conducted to identity the association between SHR and in-hospital outcomes in patients with *** A total of 12,010 patients were eventually enrolled in the *** relationship between SHR and in-hospital major adverse cardiovascular events(MACEs)was then modeled by restricted cubic spline(RCS)curves,and all patients were divided into three groups according to the *** multivariate logistic regression analysis was used to determine the associations between the SHR and in-hospital outcomes,described as odds ratios(ORs)and 95%confidence intervals(CIs).Subgroup analyses were also performed on different *** The median age of this cohort was 63(54,71)years old,and 8942(74.5%)were *** 1 was defined as SHR1(n=5763).Compared with Group 2,Group 1(OR=1.891,95%CI:1.028-3.479,P<0.001)and Group 3(OR=1.868,95%CI:1.434-2.434,P<0.001)had higher risks of suffering from in-hospital *** was associated with higher risks of in-hospital MACEs in the subgroups of DM[OR=2.282,95%CI:1.477-3.524).CONCLUSIONS Both low and high SHR levels were independently associated with in-hospital *** males with DM,hypertension,and decreased renal function had much higher risks of suffering from SHR-correlated MACEs.

关键词： acute cardiovascular finding

Simulating an Elastic Ring with Bend and Twist by an Adaptive Generalized Immersed Boundary Method

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Communications in Computational Physics 2012年第7期12卷 433-461页

作者： Boyce E.Griffith Sookkyung Lim Leon H.Charney Division of Cardiology Department of MedicineNew York University School ofMedicine550 First AvenueNew YorkNew York 10016USA Department of Mathematical Sciences University of Cincinnati839 Old Chemistry BuildingCincinnatiOhio 45221USA

Many problems involving the interaction of an elastic structure and a viscous fluid can be solved by the immersed boundary(IB)*** the IB approach to such problems,the elastic forces generated by the immersed structure are applied to the surrounding fluid,and the motion of the immersed structure is determined by the local motion of the ***,the IB method has been extended to treatmore general elasticity models that include both positional and rotational degrees of *** such models,force and torque must both be applied to the *** positional degrees of freedomof the immersed structuremove according to the local linear velocity of the fluid,whereas the rotational degrees of freedom move according to the local angular *** paper introduces a spatially adaptive,formally second-order accurate version of this generalized immersed boundary *** use this adaptive scheme to simulate the dynamics of an elastic ring immersed in *** describe the elasticity of the ring,we use an unconstrained version of Kirchhoff rod *** demonstrate empirically that our numerical scheme yields essentially second-order convergence rates when applied to such *** also study dynamical instabilities of such fluid-structure systems,and we compare numerical results produced by our method to classical analytic results from elastic rod theory.

关键词： Immersed boundary method Kirchhoff rod theory adaptive mesh refinement

NADPH oxidase： recent evidence for its role in erectile dysfunction

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Asian Journal of Andrology 2008年第1期10卷 6-13页

作者： Liming Jin Arthur L.Burnett Department of Urology The James Buchanan Brady Urological Institute Johns Hopkins Medical Institutions Baltimore MD 21287 USA

Important roles for reactive oxygen species （ROS） in physiology and pathophysiology have been increasingly recognized. Under normal conditions, ROS serve as signaling molecules in the regulation of cellular functions. However, enhanced ROS production as a result of the activation of nicotinamide adenine dinucleotide phosphate （NADPH） oxidase contributes significantly to the pathogeneses of vascular diseases. Although it has become evident that increased ROS is associated with erectile dysfunction （ED）, the sources of ROS in the penis remain largely unknown. In recent years, emergent evidence suggests the possible role of NADPH oxidase in inducing ED. In this review, we examine the relationship between ROS and ED in different disease models and discuss the current evidence basis for NADPH oxidase-derive＇d ROS in ED.

关键词： reactive oxygen species erectile function superoxide penis nitric oxide

Differences in atheroma between Caucasian and Asian subjects with anterior stroke:A vessel wall MRI study

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Stroke & Vascular Neurology 2021年第1期6卷 25-32页

作者： Hiroko Watase Mi Shen Binbin Sui Peiyi Gao Dong Zhang Jie Sun Niranjan Balu Daniel S Hippe Gail P Jarvik Xihai Zhao Rui Li Shuo Chen Chun Yuan Thomas S Hatsukami Department of Surgery University of WashingtonSeattleWashingtonUSA Department of Radiology Beijing Tiantan HospitalCapital Medical UniversityBeijingChina Tiantan Neuroimaging Center for Excellence Beijing Tiantan HospitalCapital Medical UniversityBeijingChina Beijing Neurosurgical Institute BeijingChina Department of Neurosurgery Beijing Tiantan HospitalCapital Medical UniversityBeijingChina Department of Radiology University of WashingtonSeattleWashingtonUSA Department Medicine(Medical Genetics)and Genome Sciences University of WashingtonSeattleWashingtonUSA Center for Biomedical Imaging Research Department of Biomedical EngineeringTsinghua UniversityBeijingChina

Background and purpose While extracranial carotid artery stenosis is more common among Caucasians and intracranial artery stenosis is more common among Asians,the differences in atherosclerotic plaque characteristics have not yet been extensively *** sought to investigate plaque location and characteristics within extracranial carotid and intracranial arteries in symptomatic Caucasians and Chinese using vessel wall *** Subjects with recent anterior circulation ischaemic stroke were recruited and imaged at two sites in the USA and China using similar *** extracranial carotid and intracranial arteries were reviewed to determine plaque location and *** The prevalence of extracranial carotid plaque in Caucasians and Chinese was 73.1%and 49.1%,respectively(p=0.055).Prevalence of intracranial plaque was 38.5%and 69.1%in Caucasians and Chinese,respectively(p=0.02).Furthermore,42% of Caucasians and 16%of Chinese had high-risk plaque(HRP)features(intraplaque haemorrhage,luminal surface disruption)in the extracranial carotid artery(p=0.03).The prevalence of HRP features in intracranial arteries was not significantly different between the two cohorts(4%vs 11%;p=0.42).Conclusions Differences in the location and characteristics of cerebrovascular atherosclerosis were identified by vessel wall MRI in US Caucasian and Chinese subjects with recent anterior circulation ischaemic *** carotid plaques with HRP features were more common in *** plaques were more common in Chinese subjects,but no significant difference between the two cohorts in intracranial HRP prevalence was *** studies using vessel wall imaging to investigate racial differences in cerebrovascular disease may inform underlying mechanisms of HRP development and may ultimately help guide appropriate therapy.

关键词： prevalence intracranial arteries

The AIM2 inflammasome is a central regulator of intestinal homeostasis through the IL-18/IL-22/STAT3 pathway

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Cellular & Molecular Immunology 2017年第1期14卷 127-142页

作者： Rojo A Ratsimandresy Mohanalaxmi Indramohan Andrea Dorfleutner Christian Stehlik Division of Rheumatology Department of Medicine Feinberg School of Medicine Northwestern University Chicago IL 60611 USA Robert H. Lurie Comprehensive Cancer Center Interdepartmental Immunobiology Center and Skin Disease Research Center Feinberg School of Medicine Northwestern University Chicago IL 60611 USA

Inflammasomes are important for maintaining intestinal homeostasis, and dysbiosis contributes to the pathology of inflammatory bowel disease （IBD） and increases the risk for colorectal cancer, Inflammasome defects contribute to chronic intestinal inflammation and increase the susceptibility to colitis in mice, However, the inflammasome sensor absent in melanoma 2 （AIM2） protects against coiorectal cancer in an inflammasome-independent manner through DNA-dependent protein kinase and Akt pathways, Yet, the roles of the AIM2 inflammasome in IBD and the early phases of colorectal cancer remain ill-defined, Here we show that the AIM2 inflammasome has a protective role in the intestine, During steady state, Aim2 deletion results in the loss of IL-18 secretion, suppression of the IL-22 binding protein （IL-22BP） in intestinal epithelial cells and consequent loss of the STAT3-dependent antimicrobial peptides （AMPs） Reg3β and Reg3γ, which promotes dysbiosis-linked colitis, During dextran sulfate sodium-induced colitis, a dysfunctional IL-18/IL-22BP pathway in Aim2^-/- mice promotes excessive IL-22 production and elevated STAT3 activation, Aim2^-/- mice further exhibit sustained STAT3 and Akt activation during the resolution of colitis fueled by enhanced Reg3b and Reg3g expression, This self-perpetuating mechanism promotes proliferation of intestinal crypt cells and likely contributes to the recently described increase in susceptibility of Aim2^-/- mice to colorectal cancer, Collectively, our results demonstrate a central role for the AIM2 inflammasome in preventing dysbiosis and intestinal inflammation through regulation of the IL-18/IL-22BP/IL-22 and STAT3 pathway and expression of select AMPs.

关键词： antimicrobial peptides IL-18 IL-22 IL-22BP inflammasome inflammatory bowel disease microbiome Reg3

Investigation on magnesium degradation under flow versus static conditions using a novel impedance-driven flow apparatus

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Progress in Natural Science:Materials International 2014年第5期24卷 554-560页

作者： Elbert David Mai Huinan Liu Department of Bioengineering University of California Riverside CA 92521 United States Stem Cell Center University of California Riverside CA 92521 United States Materials Science and Engineering Program University of California Riverside CA 92521 United States

This article reports a novel impedance-driven flow apparatus and its applicability for studying magnesium degradation under flow versus static conditions. Magnesium has potential to be an effective biomaterial for use inside the human body due to its biodegradability and *** undergoes degradation reactions in aqueous solutions such as body fluids, leading to mass loss and pH increase of the surrounding fluid. To compare the degradation process of magnesium under flow versus static conditions, a novel flow apparatus consisting of an impedance pump and a flow chamber was designed and constructed. In addition to low-cost, this apparatus is flexible to be sterilized and assembled, and is small enough for use inside an incubator, making it appealing for measuring and comparing magnesium degradation in vitro under flow versus static conditions. The average flow rate in this flow apparatus was 2.8 ml/s, mimicking the flow rate(2.6 ml/s) in coronary artery. In a simulated body fluid(SBF), magnesium samples lost their mass at a much faster rate under the flow condition than that under the static condition. Starting with a pH of 7.4, the SBF showed a pH increase to 8.5 under the flow condition within 96 h due to the degradation of magnesium, greater than the pH increase under the static *** results of this study demonstrated the effects of fluid flow on magnesium degradation using the impedance-driven flow apparatus, providing useful design guidelines for magnesium-based implants that may be exposed to body fluid flow.

关键词： Magnesium Degradation Corrosion Flow conditions Impedance-driven flow apparatus Impedance pump Flow device