Generation of hepatocytes from oval cell precursors in culture

Although there is experimental evidence supporting the involvement of hepatic stem cells in the pathogenesis of liver cancers, the detection and isolation of these cells remains elusive. A logical approach to detecting these cells would take advantage of their ability to differentiate (or to give rise to cells that differentiate) into hepatocytes. This approach requires an assay system that is conducive to hepatocytic differentiation. Here, we report the development of an in vitro system consisting of a three-dimensional collagen gel matrix and a fibroblast feeder layer that supports hepatocytic differentiation from precursor epithelial (oval) cell lines. The LE/2 and LE/6 oval cell lines used in this study are nontumorigenic cells that are derived from the livers of adult rats fed a choline-deficient diet containing 0.1% ethionine for 2 and 6 weeks, respectively. These lines consist of small cells that are phenotypically immature with few cytoplasmic organelles and a high nuclear-to-cytoplasmic ratio. After 4 weeks in the three-dimensional culture system, these cells acquired typical hepatocytic morphology. By electron microscopy, the cells formed canalicular structures that are typical of hepatocytes and were organelle rich, displaying peroxisomes, abundant mitochondria, and rough endoplasmic reticulum. The cells produced albumin and displayed a cytokeratin (CK) pattern typical of hepatocytes (CK 8 and CK 18-positive and CK 19-negative). The presence of a mesenchymal cell feeder layer was essential for supporting hepatocytic differentiation. Without a feeder layer but in the presence of hepatocyte growth factor and/or keratinocyte growth factor, the precursor cells formed ductal structures, suggestive of differentiation along the bile duct lineage. The three-dimensional system described provides direct proof of the lineage generation capacity of oval cells. It offers a model to study factors that may be important for hepatocytic differentiation from precursor cells and a means to assay cell populations for their ability to give rise to normal and transformed hepatocytes.     

Role of chromosome 5 in immortalization and tumorigenesis of human keratinocytes

Rhim et al. were first to show that superinfection of Ad12-SV40-infected immortalized human epidermal cells with an RNA tumor virus containing a ras oncogene, such as Ki-MSV, or their treatment with chemical carcinogens, leads to the ability of cells to both grow in anchorage-independent fashion and to form tumors in athymic nude mice. We describe details of the chromosome changes observed during the transformation. The culture was monitored through 40 passages after Ad12-SV40 infection. Chromosomes 9 and 11 showed random monosomy during the initial stages, but by passage 10 clonal evolution of the cell line was well established. Observed chromosome monosomy/trisomy coupled with chromosome rearrangements (identified as chromosomes A through F) were monosomy 13, loss of p arms of 8 and 10, partial loss of 5 (del(5)(q13) and of the q arm of 18(del(18)(q12)), and extra copies of 11q, 20 and 21. During its progression to tumorigenicity, a derived chromosome E containing a segment of 5q, also appeared to play a major role. The cells remained immortalized as long as the 5q segment was present in some of the cell population as derived chromosomes E or F. Derivative chromosome E showed noteworthy changes during the progression to tumorigenicity, in both viral and chemical transformations. There was loss of heterozygosity of 5q due to an exchange of 5q with chromosomes E or F. In Ki-MSV- and 4NQO-transformed cells, presence of an altered chromosome E (identified as E1) was observed. In MNNG-treated cells, there was a selection of population of cells with further alteration in chromosome E (identified as E3). Besides alterations in chromosome E, additional chromosome changes leading to gene activation and amplification indicating a multistep progression to tumorigenicity were observed. The cytogenetic data reiterate the ever-increasing need for molecular analysis of nonrandom karyotype changes.     

New technique for single-scan T(1) measurements using solid echoes

A simple technique for single-scan T(1) measurements in solids is proposed and analyzed for single exponential spin-lattice relaxation. In this technique, the direct spin heating caused by the sampling process is significantly reduced in comparison with conventional techniques by utilizing the 'solid echo' to refocus the magnetization. The applicability of this technique to both the solid and liquid phases is demonstrated.     

Hydrogen production via steam gasification of ash free coals

The kinetics of the coal to hydrogen conversion can be significantly enhanced by introducing catalysts. The catalysts are, however, commonly deactivated by irreversible interaction with mineral matters in coal. This work addresses hydrogen production via steam gasification of ash free coals. Following the production of ash free coals (AFCs) derived from various raw coals (brown, bituminous, and coking coal), fixed-bed steam gasification of the AFCs was performed as a function of temperature and which was compared with one another and also with that of the matching raw coals. In the absence of a catalyst, AFCs produced from different parent coals exhibited similarly low gasification reactivity, comparable to a high rank coal (coking coal) at 700 °C. As expected, the reaction became faster with increasing temperature in the range, 700–900 °C. The steam gasification of AFCs was highly activated by K₂CO₃ above 700 °C. It was very likely that water–gas shift reaction associated with the gasification of AFCs was also catalyzed.     

Aryl Biphenyl‐3‐ylmethylpiperazines as 5‐HT7 Receptor Antagonists

The 5‐HT₇ receptor (5‐HT₇R) is a promising therapeutic target for the treatment of depression and neuropathic pain. The 5‐HT₇R antagonist SB‐269970 exhibited antidepressant‐like activity, whereas systemic administration of the 5‐HT₇R agonist AS‐19 significantly inhibited mechanical hypersensitivity and thermal hyperalgesia. In our efforts to discover selective 5‐HT₇R antagonists or agonists, aryl biphenyl‐3‐ylmethylpiperazines were designed, synthesized, and biologically evaluated against the 5‐HT₇R. Among the synthesized compounds, 1‐([2′‐methoxy‐(1,1′‐biphenyl)‐3‐yl]methyl)‐4‐(2‐methoxyphenyl)piperazine ( 28 ) was the best binder to the 5‐HT₇R (pK_i=7.83), and its antagonistic property was confirmed by functional assays. The selectivity profile of compound 28 was also recorded for the 5‐HT₇R over other serotonin receptor subtypes, such as 5‐HT₁R, 5‐HT₂R, 5‐HT₃R, and 5‐HT₆R. In a molecular modeling study, the 2‐methoxyphenyl moiety attached to the piperazine ring of compound 28 was proposed to be essential for the antagonistic function.     

Comparison of the Microhardness and Morphology of Five Different Retrograde Filling Materials in Aqueous and Dry Conditions

The purpose of the present study was to compare the effect of dry and aqueous conditions on the surface morphology and surface hardness of five materials 24 h after being used as fillings without initial setting time in dry condition. The five materials were ProRoot mineral trioxide aggregate (MTA), super EBA, intermediate restorative materials (IRM), zinc oxide eugenol (ZOE), and amalgam. To evaluate microhardness, the five materials were submitted to the Vickers microhardness (VHN) test. We used a scanning electron microscope (Steroscan 440, Leica Cambridge, England) to observe the microstructural morphology of the five different materials. The VHN of MTA soaked in water showed five times lower than that of MTA soaked in dry condition. On the other hand, super EBA was less influenced by the medium of storage compared with the other materials. Scanning electron microscope (SEM) images showed the similar results with microhardness tests. The surface of MTA soaked in water appeared to be unstable compared with that of dry condition while super EBA showed similarly smooth surface in both conditions (aqueous and dry). In conclusion, the physical property of MTA is reduced after storage in water; however, super EBA is less influenced by aqueous condition. SCANNING 34: 359‐366, 2012. © 2012 Wiley Periodicals, Inc.     

Copper-based nanoparticles for biopolymer-based functional films in food packaging applications

This review summarizes the latest developments in the design, fabrication, and application of various Cu-based nanofillers to prepare biopolymer-based functional packaging films, focusing on the effects of inorganic nanoparticles on the optical, mechanical, gas barrier properties, moisture sensitivity, and functional properties of the films. In addition, the potential application of Cu-based nanoparticle-added biopolymer films for fresh food preservation and the effect of nanoparticle migration on food safety were discussed. The incorporation of Cu-based nanoparticles improved the film properties with enhanced functional performance. Cu-based nanoparticles such as copper oxide, copper sulfide, copper ions, and copper alloys affect biopolymer-based films differently. The properties of composite films containing Cu-based nanoparticles depend on the concentration of the filler, the state of dispersion, and the interaction of the nanoparticles with the biopolymer matrix in the film. The composite film filled with Cu-based nanoparticles effectively extended the shelf life by maintaining the quality of various fresh foods and securing safety. However, studies on the migration characteristics and safety of copper-based nanoparticle food packaging films are currently being conducted on plastic-based films such as polyethylene, and research on bio-based films is limited.     

Comparative studies on steam gasification of ash-free coals and their original raw coals

Catalytic gasification of raw coals at mild condition is not realized yet mainly due to deactivation of catalysts via their irreversible interaction with mineral matters in coal. As a means to achieve repeated use of catalysts, four different ash-free coals (AFCs) containing less than 0.2 wt% ash are produced in this work. Steam gasification of ash-free coals (AFCs) and their parent raw coals of various ranks ranging from lignite (Eco) to coking coal (Posco) is performed in a fixed bed reactor at 700–900 °C. Regardless of the rank of the parent raw coals, all the AFCs behave like a highly carbonized coal such that their gasification rate are similarly slow and they exhibit relatively low H₂/CO ratio. The steam gasification and associated CO to CO₂ conversion of the AFCs are, however, significantly enhanced by K₂CO₃, resulting in the higher H₂/CO and CO₂/CO molar ratio.     

Experiments of optimal delay extraction algorithm using adaptive time-delay filter for improved vibration suppression

In the previously introduced direct adaptive command shaping filter (ACSF), the time-delay value is fixed and only the magnitudes of the impulses are learned. The performance of the direct adaptive time-delay command shaping filter, however, depends on the select time-delay. In this paper, the authors introduce a new scheme to extract the optimal time-delay value for the improved vibration suppression in flexible motion system. To develop the optimal time-delay extraction scheme, the authors have analyzed the effect of the time-delay value on the performance of the direct ACSF. Based on the analysis result the authors have established a set of equations to extract the optimal time-delay toward the optimal vibration suppression performance of ACSF. Experimental results using a gantry robot with a single flexible link show the effectiveness of the proposed time-delay adaptation approach for the improved vibration suppression. This paper was presented at the 4th Asian Conference on Multibody Dynamics(ACMD2008), Jeju, Korea, August 20–23, 2008. Joo Han Park received the B.S. and M.S. degrees in Mechanical Engineering from the Kyung Hee University, Korea, in 2005 and 2007. He is currently a candidate for the PhD at Kyung Hee University, Korea. His research interests include robotics and vibration control. Sungsoo Rhim received his B.S. and M.S. degrees in Mechanical Engineering from Seoul National Univ., Korea, in 1990 and 1992 respectively. He then received his Ph.D. degree from Georgia Institute of Technology in 2000. He worked for CAMotion, Inc. in GA, USA, as Research Director from 2000 until 2003 and he is currently an Assistant Professor at the Dept. of Mechanical Engineering in Kyung Hee Univ., Korea. His research interests include system dynamics, control, robotics and vibration.     

Thermodynamic Analysis of Water Vapor Sorption Isotherms and Mechanical Properties of Selected Paper-Based Food Packaging Materials

ABSTRACT:  Adsorption isotherms of 3 selected paper-based packaging materials, that is, vegetable parchment (VP) paper, Kraft paper, and solid-bleached-sulfate (SBS) paperboard, were determined at 3 different temperatures (25, 40, and 50 °C). The GAB isotherm model was found to fit adequately for describing experimental adsorption isotherm data for the paper samples. The monolayer moisture content of the paper samples decreased with increase in temperature, which is in the range of 0.0345 to 0.0246, 0.0301 to 0.0238, and 0.0318 to 0.0243 g water/g solid for the MG paper, the Kraft paper, and the SBS paperboard, respectively. The net isosteric heats of sorption ( q_st ) for the paper samples decreased exponentially with increase in moisture content after reaching the maximum values of 18.51, 27.39, and 26.80 kJ/mol for the VP paper, the Kraft paper, and the SBS paperboard, respectively, at low-moisture content. The differential enthalpy and entropy of 3 paper samples showed compensation phenomenon with the isokinetic temperature of 399.7 K indicating that water vapor had been adsorbed onto the paper samples with the same mechanism. Depending on the paper material, tensile strength of paper samples was affected by moisture content.