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IMAGING RNA IN LIVING CELLS WITH MOLECULAR BEACONS:CURRENT PERSPECTIVES AND CHALLENGES

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Journal of Innovative Optical Health Sciences 2009年第4期2卷 315-324页

作者： ANTONY k.chen ANDREW TSOURkAS Department of Bioengineering University of Pennsylvania PhiladelphiaPA 19104USA

There is a growing realization that cell-to-cell variations in gene expression have importantbiological consequences underlying phenotype diversity and cell fate. Although analytical toolsfor measuring gene expression, such as DNA microarrays, reverse-transcriptase PCR and in situhybridization have been widely utilized to discover the role of genetic variations in governingcellular behavior, these methods are performed in cell lysates and/or on fixed cells, and thereforelack the ability to provide comprehensive spatial-dynamic information on gene expression. Thishas invoked the recent development of molecular imaging strategies capable of illuminatingthe distribution and dynamics of RNA molecules in living cells. In this review, we describe aclass of molecular imaging probes known as molecular beacons (MBs), which have increasinglybecome the probe of choice for imaging RNA in living cells. In addition, we present the majorchallenges that can limit the ability of MBs to provide accurate measurements of RNA, anddiscuss efforts that have been made to overcome these challenges. It is envisioned that withcontinued refinement of the MB design, MBs will eventually become an indispensable tool foranalyzing gene expression in biology and medicine.

关键词： Gene expression fluorescence probes molecular imaging biosensor

Surface acoustic wave sensor system applied to the kinetic study of urease in plant seeds

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Chinese Journal of Chemistry 1995年第3期13卷 231-240页

作者： LIU, DZ chen, k GE, k NIE, LH YAO, SZ HUNAN UNIV NEW MAT RES INSTCHANGSHA 410082PEOPLES R CHINA

A new type of the surface acoustic wave (SAW) sensor system was delivered. Urease from several kinds of plant seeds was extracted with different extracting solvents. The urease activity, Michaelis constant and other kinetic parameters were estimated for the first time by means of the new device-SAW sensor system. Some factors such as pH, temperature, activators and inhibitors are also discussed. The method can be applied to the determination of urea content in human urine and the experimental results consist with those reported.

关键词： SURFACE ACOUSTIC WAVE SENSOR UREASE UREA kINETIC PARAMETERS

Primary porcine hepatocytes with portal vein serum cultured on microcarriers or in spheroidal aggregates

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World Journal of Gastroenterology 2000年第3期6卷 365-370页

作者： Gao Y Hu HZ chen k Yang JZ First Mil Med Univ Zhujiang Hosp Dept Hepatobiliary Surg Guangzhou 510282 Guangdong Provi Peoples R China

AIM To develop a culture mode providingdurable biomaterials with high yields andactivities used in bioartificial *** Hepatocytes were isolated from awhole pig liver by Seglen’s method of orthotopicperfusion with *** culture onmicrocarriers,primary porcine hepatocyteswere inoculated at a concentration of 5×10~7/mLinto the static culture systems containing 2 g/LCytodex-3,then supplemented with 100 mL/Lfetal calf serum(FCS)or 100 mL/L porcineportal vein serum(PPVS)*** aggregate culture hepatocytes wereinoculated into 100 mL siliconized flasks at aconcentration of 5.0×10~6/*** In culture on microcarriershepatocytes tended to aggregate on Cytodex-3obviously after being *** multi-cellular aggregated spheroids could be found inthe two systems 24 h-48 h after hepatocyteswere *** morphological charact-eristics and synthetic functions were maintainedfor 5 wk in FCS culture system and 8 wk in PPVSculture *** spheroidal aggregate cultureabout 80%-90% isolated hepatocytes becameaggregated spheroids 24h after cultured insuspension and mean diameter of the spheroidswas 100μ*** relationship among thehepatocytes resembled that in the liver in *** functions of albumin and urea of the spheroids were twice those of hepatocytescultured on *** As high-yields and high-activitymodes of culture on microcarriers or inspheroidal aggregate culture with portal veinserum are promising to provide biomaterials forbioartificial liver(BAL)efficiently.

关键词： porcine hepatocytes microcarriers cell culture spheroidal aggregate culture portal vein serum

Prediction of particle size and layer-thickness distributions in a continuous horizontal fluidized-bed coating process

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Particuology 2020年第3期18卷 1-12页

作者： P.Bachmann k.chen A.Buck E.Tsotsas Thermal Process Engineering Otto-von-Guericke UniversityUniversit(a)tsplatz 2Magdeburg D-39106Germany Institute of Particle Technology Friedrich-Alexander University Erlangen-NurembergCauerstr.4Erlangen D-91058Germany

To predict the particle size and layer-thickness distributions(LTDs)in a continuously operated horizontal fluidized-bed granulation process,two alternative models were considered.A one-dimensional two-zone model was proposed,which describes with population-balance equations the particle growth in a spraying zone that is separated from the drying *** residence-time distribution(RTD)was calculated from a literature correlation and was coupled with a population-balance model via a tank-in-series model with reflux.A two-dimensional,one-zone population-balance model,which was based directly on the RTD and the feed particle-size distribution(PSD)was also *** experiments were conducted and analyzed microscopically and with a camera optical device to determine the sample *** over the particle population were derived from the PSDs and were analyzed directly by *** compare the simulated data with the experimentally determined distributions,the PSDs were converted to *** good agreement shows that both methods are suitable to determine the PSD from an RTD of an arbitrary granulation process in a horizontal fluidized *** appears necessary with regards to the LTD spread.

关键词： Fluidized bed Continuous process Coating,Residence-time distribution Particle-size distribution Layer-thickness distribution

Reconstructing and forecasting the COVID-19 epidemic in the United States using a 5-parameter logistic growth model

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Global Health Research and Policy 2020年第1期5卷 221-227页

作者： Ding-Geng chen Xinguang chen Jenny k.chen School of Social Work University of North CarolinaTate-Turner Kuralt Building 548-CCB#3550Chapel HillNC 27599USA Department of Statistics University of PretoriaPretoriaSouth Africa Department of Epidemiology University of FloridaGainesvilleUSA Department of Statistics and Data Science Cornell UniversityIthacaUSA

Background:Many studies have modeled and predicted the spread of COVID-19(coronavirus disease 2019)in the *** data that begins with the first reported ***,the shortage of testing services to detect infected persons makes this approach subject to error due to its underdetection of early cases in the *** new approach overcomes this limitation and provides data supporting the public policy decisions intended to combat the spread of COVID-19 ***:We used Centers for Disease Control and Prevention data documenting the daily new and cumulative cases of confirmed COVID-19 in the *** January 22 to April 6,2020,and reconstructed the epidemic using a 5-parameter logistic growth *** fitted our model to data from a 2-week window(i.e.,from March 21 to April 4,approximately one incubation period)during which large-scale testing was being *** parameters obtained from this modeling,we reconstructed and predicted the growth of the epidemic and evaluated the extent and potential effects of ***:The data fit the model *** estimated daily growth rate was 16.8%overall with 95%CI:[15.95,17.76%],suggesting a doubling period of 4 *** on the modeling result,the tipping point at which new cases will begin to decline will be on April 7th,2020,with a peak of 32,860 new cases on that *** the end of the epidemic,at least 792,548(95%CI:[789,162,795,934])will be infected in the *** on our model,a total of 12,029 cases were not detected between January 22(when the first case was detected in the U.S.)and April ***:Our findings demonstrate the utility of a 5-parameter logistic growth model with reliable data that comes from a specified period during which governmental interventions were appropriately *** informing public health decision-making,our model adds a tool for more faithfully capturing the spread of the COVID-19 epidemic.

关键词： COVID-19 Epidemics Disease dynamics Population-based model Logistic growth model Prediction Reconstruction Under-detection Tipping point USA

Laparoscopic wedge resection of synchronous gastric intraepithelial neoplasia and stromal tumor:A case report

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World Journal of Gastroenterology 2010年第39期16卷 5005-5008页

作者： Mou YP Xu XW Xie k Zhou W Zhou YC chen k. Department of General Surgery Sir Run Run Shaw Hospital School of Medicine Zhejiang University 3 East Qingchun road Hangzhou 310016 Zhejiang Province China. xuxiaowu77@***

Synchronous occurrence of epithelial neoplasia and gastrointestinal stromal tumor(GIST)in the stomach is *** rare cases have been reported in the *** present here a 60-year-old female case of synchronous occurrence of gastric high-level intraepithelial neoplasia and GIST with the features of 22 similar cases and detailed information reported in the Englishlanguage literature *** the present patient,epithelial neoplasia and GIST were removed en bloc by laparoscopic wedge *** the best of our knowledge,this is the first reported case treated by laparo-scopic wedge resection.

关键词： Laparoscopy Stomach neoplasm Gastrointestinal stromal tumor Gastrectomy Synchronous neoplasm

Engineering Novel Molecular Beacon Constructs to Study Intracellular RNA Dynamics and Localization

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Genomics, Proteomics & Bioinformatics 2017年第5期15卷 279-286页

作者： Zhao Ma Xiaotian Wu Christopher J.krueger Antony k.chen Department of Biomedical Engineering College of Engineering Peking University Beijing 100871 China Wallace H Coulter Department of Biomedical Engineering Georgia Institute of Technology Atlanta GA 30332 USA

With numerous advancements in novel biochemical techniques, our knowledge of the role of RNAs in the regulation of cellular physiology and pathology has grown significantly over the past several decades. Nevertheless, detailed information regarding RNA processing, trafficking, and localization in living cells has been lacking due to technical limitations in imaging single RNA transcripts in living cells with high spatial and temporal resolution. In this review, we discuss tech- niques that have shown great promise for single RNA imaging, followed by highlights in our recent work in the development of molecular beacons （MBs）, a class of nanoscale oligonucleotide-probes, for detecting individual RNA transcripts in living cells. With further refinement of MB design and development of more sophisticated fluorescence microscopy techniques, we envision that MB-based approaches could promote new discoveries of RNA functions and activities.

关键词： Y-O-methyl RNA Phosphorothioate Molecular beacon RNA dynamics Single-molecule RNAimaging

A 2-D FINITE ELEMENT MODEL SIMULATION OF THE MELTING PROCESS OF Al-Ti ALLOY IN VACUUM INDUCTION FURNACE WITH COLD CRUCIBLE(VIFCC)

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Acta Metallurgica Sinica(English Letters) 2004年第3期17卷 229-237页

作者： S.C.Chu S.S.Lian F.k.chen Institute of Materials Science and Engineering National Taiwan UniversityTaibei(Taipei)Institute of Materials Science and EngineeringNational Taiwan UniversityTaibei(Taipei)Institute of Mechanical EngineeringNational Taiwan UniversityTaibei(Taipei)

The development of a numerical model for the melting process of Al--Ti alloy targetmaterial in vacuum induction furnace with cold crucible (VIFCC)was described. It isa two--dimensional computational methodology to calculate electromagnetic field, heattransfer field and fluid flow field. Based on the aid of the finite element method withthe commercial software--ANSYS, a superimposition method of a layer of copper anda slit to simulate the VIFCC melting process was used. The method was effectiveto save large quantity of memory and computing time. Meanwhile, a temperaturedistribution profile during the melting process was obtained. Validity of the model wasconfirmed by comparison between the result from calculation and those from directmeasurement by optical pyrometer and indirect investigation by ingot macrostructure.A relatively good agreement was found. Further, a nearly directional solidificationstrvcture was obtained under properly controlling the cooling rate and heating power.Therefore, such model developed in this article is feasible.

关键词： VIFCC ANSYS superimposition ingot macrostructure

BEHAVIOR OF FLOW STRESS OF ALUMINUM SHEETS USED FOR PRESSURE CAN DURING COMPRESSION AT ELEVATED TEMPERATURE

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Acta Metallurgica Sinica(English Letters) 2005年第6期18卷 756-762页

作者： G.S. Fu W.Z. chen k. W. Qian School of Mechanical Engineering Fuzhou University Fuzhou 350002 China

The behavior of flow stress of Al sheets used for pressure can prepared by different melt-treatment during plastic deformation at elevated temperature was studied by isothermal compression test using Gleeble1500 dynamic hot-simulation testing machine. The results show that the AI sheets possess the remarkable characteristic of steady state flow stress when they are deformed in the temperature range of 350-500℃ at strain rates within the range of 0.01-10.0s^-1. A hyperbolic sine relationship is found to correlate well the flow stress with the strain rate, and an Arrhenius relationship with the temperature, which implies that the process of plastic deformation at elevated temperature for this material is thermally activated. Compared with the AI pieces prepared by no or conventional melt-treatment, hot deformation activation energy of AI sheets prepared by high-efficient melt-treatment is the smallest （ Q= 168.0kJ/mol）, which reveals that the hot working formability of this material is very better, and has directly to do with the effective improvement of its metallurgical quality.

关键词： Al sheets used for can melt-treatment plastic deformation at elevatedtemperature flow stress hot deformation activation energy