Interaction of human retinal RGS with G-protein alpha-subunits

The effects of leptin on insulin secretion from pancreatic islets of Sprague-Dawley rats were examined in vitro. In a basal glucose medium (5.5 mM), insulin secretion from isolated islets was significantly decreased after addition of a recombinant leptin (80 nM) (3.20+/-0.14 nmol/10 islets/h) compared with that before the addition (4.41+/-0.30 nmol/10 islets/h). Although significant leptin suppression of insulin secretion was not observed under a glucose-stimulated (11.1 mM) condition, these results suggest that a negative feedback system may exist between leptin and insulin, which increases the production of leptin from adipose tissues.     

The chitin catabolic cascade in the marine bacterium Vibrio furnissii. Molecular cloning, isolation, and characterization of a periplasmic chitodextrinase

Chitin catabolism in Vibrio furnissii comprises several signal transducing systems and many proteins. Two of these enzymes are periplasmic and convert chitin oligosaccharides to GlcNAc and (GlcNAc)2. One of these unique enzymes, a chitodextrinase, designated EndoI, is described here. The protein, isolated from a recombinant Escherichia coli clone, exhibited (via SDS-polyacrylamide gel electrophoresis) two enzymatically active, close running bands ( approximately mass of 120 kDa) with identical N-terminal sequences. The chitodextrinase rapidly cleaved chitin oligosaccharides, (GlcNAc)4 to (GlcNAc)2, and (GlcNAc)5,6 to (GlcNAc)2 and (GlcNAc)3. EndoI was substrate inhibited in the millimolar range and was inactive with chitin, glucosamine oligosaccharides, glycoproteins, and glycopeptides containing (GlcNAc)2. The sequence of the cloned gene indicates that it encodes a 112,690-kDa protein (1046 amino acids). Both proteins lacked the predicted N-terminal 31 amino acids, corresponding to a consensus prokaryotic signal peptide. Thus, E. coli recognizes and processes this V. furnissii signal sequence. Although inactive with chitin, the predicted amino acid sequence of EndoI displayed similarities to many chitinases, with 8 amino acids completely conserved in 10 or more of the homologous proteins. There was, however, no "consensus" chitin-binding domain in EndoI.     

Experimental analysis of off-take phenomena at the header–feeder system of CANDU

An experimental study has been performed to investigate the off-take phenomena at the T-junction installed between the header and feeder pipes in CANadian Deuterium Uranium (CANDU) reactor. Previous works have been made to correlate the onset condition and the quality at the branch for the representative directions such as top, side and bottom. However, for the actual branches with specific direction such as ±36° and ±72° to the horizontal header in the header–feeder system of CANDU, the direct application of the conventional correlations to the safety analysis needs experimental verification. A 1/2 scaled test facility from the prototype plant of Wolsong Units 2, 3 and 4 (CANDU 6 type) is used to measure the onset conditions for the gas pull though and liquid entrainment in the seven different orientations of the branch pipe with 0°, ±36°, ±72° and ±90° angles. The horizontal pipe has a diameter of 184 mm. The branch pipes are attached on the horizontal pipe with, and have diameters of 16.7, 20.7 and 24.8 mm, respectively. Air and water are used as working fluids under the conditions of room temperature and of pressures up to 0.95 MPa. The present experimental data were compared with the existing experimental data set such as UCB and KfK and with the horizontal stratification entrainment model (HSEM) in RELAP5/MOD3.3. It was found that The HSEM does not show good agreements with the present data obtained from the specific branch angles, ±36° and ±72°. At the bottom branch, the quality data are compared with the previous data in terms of h/D. The present data can be used for an improvement of the off-take model in order to predict the onset of off-take and the branch quality at specific angles between −90° and +90° in CANDU.     

激光合金化熔化区电子显微分析

本文采用5kW横流二氧化碳激光器进行了Fe-Ni-Cr合金涂层和45号钢基体合金化处理,用电子显微术分析了熔化区的特征,揭示了所谓激光“亮带”的本质。结果表明,“亮带”属于熔化区;是平面晶一个纵切断面,其宽度等于平面晶的高度,随扫描速度的增加和激光功率的减小而变窄。     

燃气PE管施工质量通病及应对措施

文章例举了目前在PE管施工中普遍存在的一些具有代表性的质量问题,通过对其成因进行分析,提出了相应的应对措施。     

Sequence elements required for apolipoprotein B mRNA editing enhancement activity from chicken enterocytes

Mammalian intestinal apolipoprotein B (apoB) mRNA edits codon 2153 from CAA in apoB100 mRNA to a stop codon (UAA) in apoB48 mRNA. By contrast, chicken intestinal apoB mRNA contains a CAA codon at the corresponding site, but is not edited. Chicken enterocyte S100 extracts fail to edit mammalian apoB RNA, but contain factor(s) which enhance the mammalian enterocytes editing activity. By converting the chicken apoB mooring sequences to the conserved mammalian sequences, the study confirmed that this 11-nucleotide stretch was necessary and sufficient for minimal RNA editing. Using rat and chicken apoB chimeric constructs, the study revealed that mammalian apoB sequences were required for editing enhancement. In concert with the 29-nucleotide conserved cassette, the 5' rat apoB element (nucleotides 6615-6629) increased editing at C-6666, and was necessary for editing enhancement of chicken enterocyte S100 extracts. Similarly, the 3' rat apoB element (nucleotides 6726-6752) was required for editing enhancement of chicken enterocyte S100 extracts, but to a lesser extent in efficiency, compared to the 5' region. In conclusion, this study identified the sequences required for editing enhancement activity from chicken enterocyte S100 extracts.     

冲压成型与滚压成型的应用与比较

冲压成型和滚压成型是机械制造业的两种加工方式，各有特点并在实际生产中均有大量的应用，文中通过具体零件的加工过程，对两种成型方式进行比较。     

某车组合导航系统研究

该文论述了战车建立组合导航的必要性并分析了几种组合导航方式的优缺点。结合现有软硬件资源,确定了某车组合导航的方案,提出了实现某车组合导航中的难点。根据模拟试验的结果,说明在该车上实现组合导航是完全可行的。     

Alteration of the pharmacokinetics of small proteins by iodination

The pharmacokinetics of several proteins were investigated using two different assays. A 23 kDa recombinant protein fragment of bactericidal/permeability-increasing protein (rBPI23) was radiolabeled with 125I using Iodo-beads and administered rats. Plasma samples were collected and assayed for 125I-rBPI23 by radioactivity. In a separate experiment, rBPI23 was administered to rats and plasma samples were assayed for rBPI23 by ELISA. The clearance determined from plasma concentrations of 125I-rBPI23 measured by radioactivity was about 2.5-fold lower than that of rBPI23 determined by ELISA. In addition, the steady state volumes of distribution and mean residence times of 125I-rBPI23 measured by radioactivity were four-fold and 10-fold greater, respectively, compared to those measured by the ELISA method. By studying several proteins with a range of molecular weights, we found that the pharmacokinetics of proteins below about 60 kDa were different when assayed by radioactivity or ELISA, but those of proteins with molecular weights of at least 80 kDA revealed only minor differences. To determine which assay method yielded the correct plasma pharmacokinetic profile, rBPI23 was metabolically labeled with 35S-methionine and administered to rats, and plasma samples were assayed by radioactivity. The concentration-time profile assessed by this method was very close to that determined by ELISA. Exposing rBPI23 to chloramine-T (the oxidant used in the iodination process) and measuring its plasma concentration by ELISA revealed pharmacokinetics similar to those of the iodinated protein measured by radioactivity. In contrast, radiolabeling rBPI23 using iodinated Bolton-Hunter reagent (which avoids exposing the protein to oxidant), and measuring 125I-rBPI23 by radioactivity, yielded pharmacokinetics that were similar, although not identical, to the pharmacokinetics of rBPI23 measured by ELISA. Thus, our data suggest that directly iodinating low-molecular-weight proteins by oxidation procedures alters their clearance from the blood, preventing reliable determination of pharmacokinetic parameters.