Analytical characterization and purification of plasma membrane from cultured hepatoma cells (HTC cells)

The plasma membrane of the hepatoma cell line, HTC cells, has been characterized and purified by cell fractionation techniques. In the absence of true 5′-nucleotidase in HTC cells, alkaline phosphodiesterase I has been used as a marker enzyme, following conclusions gained from differential and isopycnic centrifugation studies (Lopez Saura, P., Trouet A. and Tulkens P. (1978) Biochim. Biophys. Acta 543, 430–449). To confirm this localization, HTC cells were exposed to anti-plasma membrane IgG at 4°C and fractionated. Alkaline phosphodiesterase I and IgG showed super imposable distribution patterns in linear sucrose gradients. Alkaline phosphodiesterase I is, however, only poorly resolved from enzyme markers of other organelles, especially NADPH-cytochrome $\text{c}$ reductase (endoplasmic reticulum) and galactosyltransferase (Golgi complex). Maximal purification from the homogenate is only 13-fold, on a protein basis, even when using a microsomal fraction (67 and 13% of alkaline phosphodiesterase I and protein, respectively) as the starting material. Improved resolution can be obtained after the addition of small quantities of digitonin (equimolar with respect to the cholesterol content). Digitonin increases the buoyant density of alkaline phosphodiesterase I by approx. 0.05 g/cm³, whereas the buoyant densities of galactosyltransferase and NADPH-cytochrome $\text{c}$ reductase are increased only by 0.03 and 0.015 g/cm³, respectively. Accordingly, a procedure has been designed which yields a fraction containing 22.8% of alkaline phosphodiesterase I with a purification of 21-fold on a protein basis. The content of NADPH-cytochrome $\text{c}$ reductase and galactosyltransferase is 1.2 and 2.1%, respectively. Electron microscopy shows smooth surface membrane elements and vesicles, with only occasional other recognizable elements.     

Effect of protease inhibitors on protein degradation in rat hepatoma cells I. Effect on general protein degradation

Tosyllysine chloromethyl ketone and tosylphenylalanine chloromethyl ketone in vitro are active-site specific and irreversible inhibitors of trypsin (EC 3.4.21.4) and chymotrypsin (EC. 3.4.21.1) respectively. Using rat hepatoma cells in suspension culture, both inhibitors were found to partially inhibit breakdown of prelabelled cell proteins ot amino acids, the effect being greastest in the absence of serum. Protein synthesis in rat hepatoma cells, reticulocytes and reticulyte lysates was also irreversibly inhibited by these compounds. Reduction of ATP levels with antimycin a inhibited protein degradation, but neither tosylphenylalanine chloromethyl ketone nor tosyllysine chloromethyl ketone had any effect on ATP concentration in rat hepatoma cells. These results suggest that the degradation of at least some proteins in animal cells may involve the action of serine protease(s).     

Evaluation of Integrated Anaerobic Digestion and Hydrothermal Carbonization for Bioenergy Production

Lignocellulosic biomass is one of the most abundant yet underutilized renewable energy resources. Both anaerobic digestion (AD) and hydrothermal carbonization (HTC) are promising technologies for bioenergy production from biomass in terms of biogas and HTC biochar, respectively. In this study, the combination of AD and HTC is proposed to increase overall bioenergy production. Wheat straw was anaerobically digested in a novel upflow anaerobic solid state reactor (UASS) in both mesophilic (37 °C) and thermophilic (55 °C) conditions. Wet digested from thermophilic AD was hydrothermally carbonized at 230 °C for 6 hr for HTC biochar production. At thermophilic temperature, the UASS system yields an average of 165 L_CH4/kg_VS (VS: volatile solids) and 121 L _CH4/kg_VS at mesophilic AD over the continuous operation of 200 days. Meanwhile, 43.4 g of HTC biochar with 29.6 MJ/kg_{dry_biochar} was obtained from HTC of 1 kg digestate (dry basis) from mesophilic AD. The combination of AD and HTC, in this particular set of experiment yield 13.2 MJ of energy per 1 kg of dry wheat straw, which is at least 20% higher than HTC alone and 60.2% higher than AD only.     

不同细胞周期大鼠肝实质细胞癌细胞粘弹特性研究

以胸腺嘧啶核苷和秋水仙碱顺序阻断法及胸腺嘧啶核苷双阻断法分别获得同步化Ｇ１期和Ｓ期细胞,从细胞周期角度出发,采用微管吸吮技术对大鼠肝实质细胞癌细胞的粘弹特性进行了测定并以标准线性固体模型对实验数据进行了拟合,结果表明：该细胞具有高弹性和低粘性的总体特征;Ｇ１期细胞与Ｓ期细胞相比具有高Ｋ１值和低μ值的特点,从而显示Ｇ１期细胞比Ｓ期细胞具有更大的强度和更快的被动变形能力。这些结果不仅反映了同步化细胞存在的细胞骨架状态的周期性差异,也提示Ｇ１期细胞可能比Ｓ期细胞更适于在血流中存活和转移。     

Feasibility of using a fully immersive virtual reality system for kinematic data collection

Commercially-available Virtual Reality (VR) systems have the potential to be effective tools for simultaneous visual manipulation and kinematic data collection. Previously, these systems have been integrated with research-grade motion capture systems to provide both functionalities; however, they are yet to be used as stand-alone systems for kinematic data collection. The present study aimed to validate the HTC VIVE VR system for kinematic data collection by evaluating the accuracy of its position and orientation signals. The VIVE controller and tracker were each compared to a Polhemus Liberty magnetic tracking system sensor for angular and translational measurement error and signal drift. A sensor from each system was mounted to opposite ends of a rigid segment which was driven through fifty rotations and fifty translations. Mean angular errors for both the VIVE tracker and controller were below 0.4°. Mean translational error for both sensors was below 3 mm. Drift in the Liberty signal components was consistently lower than drift in VIVE components. However, all mean rotational drift measures were below 0.1° and all mean translational measures were below 0.35 mm. These data indicate that the HTC VIVE system has the potential to be a valid and reliable means of kinematic data collection. However, further investigation is necessary to determine the VIVE’s suitability for capturing extremely minute or high-volume movements.     

中国人HLA纯合细胞的筛选及纯合性鉴定

本文报告了我们实验室在中国人中筛选HLA纯合子的方法和筛选流程。用HLA血清学分型法,从上海129个近亲婚配家庭中筛选到HLA-AB纯合子23个(分布于17个家庭)。其中19个HLA-AB纯合子(分布于14个家庭)进一步做了家系MLC棋盘。最终证明,它们中14个细胞(分布于10个家庭)的HLA-D位点也纯合。     

Effect of protease inhibitors on protein degradation in rat hepatoma cells II. Effects on ornithine decarboxylase and tyrosine aminotransferase

Tosyllysine chloromethyl ketone and tosylphenylalanine chloromethyl ketone in vitro are active-site specific and irreversible inhibitors of trypsin (EC 3.4.21.4) and chymotrypsin (EC. 3.4.21.1) respectively. Using rat hepatoma cells in suspension culture, both inhibitors were found to partially inhibit breakdown of prelabelled cell proteins ot amino acids, the effect being greastest in the absence of serum. Protein synthesis in rat hepatoma cells, reticulocytes and reticulyte lysates was also irreversibly inhibited by these compounds. Reduction of ATP levels with antimycin a inhibited protein degradation, but neither tosylphenylalanine chloromethyl ketone nor tosyllysine chloromethyl ketone had any effect on ATP concentration in rat hepatoma cells. These results suggest that the degradation of at least some proteins in animal cells may involve the action of serine protease(s).     

Inhibition of arachidonate biosynthesis in hepatoma tissue culture cells by 11-deoxycorticosterone-induced factor

In this work it was demonstrated that the incubation of hepatoma cultured cells (HTC 7288 c) with 11-deoxycorticosterone (DOC) ranging from 0 to 10^–4M concentration provoked a dose-dependent inhibition in the conversion of [1^–14C] eicosatrienoic acid to arachidonic acid. This steroid also produced an increase in the uptake of exogenous 20: 3 (n-6) acid. The depressive effect evoked by DOC on 5 desaturating activity was reflected on the fatty acid composition changes of the hepatoma cells. The 5 desaturase activity was inhibited by a soluble factor that would be induced by the hormone and that was present in the cytosol fraction from DOC-treated cells, corresponding to a low molecular mass below 25 kDa. Presently we report that an 11--OH group on the steroid molecule is not an essential requirement for the production of a 5 desaturase inhibitory factor.Members of the Carrera del Investigador Científico, CONICET, Argentina