Effects of two free radical scavengers and intermittent warming on chilling injury and polar lipid composition of cucumber and sweet pepper fruits

Cucumber (Cucumis sativus L.) and sweet pepper (Capsicum annuumL.) fruits were chilled at 2.5?C for different periods and thentransferred to 20?C and subsequently evaluated for chillinginjury. Sodium benzoate at 10 nw or ethoxyquin at 9.2 mM, appliedas a 5-min dip before chilling, increased the degree of unsaturationof 18-carbon fatty acids in the polar lipids and reduced theseverity of chilling injury. Intermittent warming to 20?C for24 hr at 3-day intervals also alleviated the chilling symptomsand increased fatty acid unsaturation of the polar lipids incucumber and pepper fruits. (Received August 22, 1978; )     

蛇毒抗肝癌作用的研究

眼镜蛇毒具有抗肝癌作用.我们采用多种小鼠移植性肝癌研究了眼镜蛇毒抗肝癌作用.通过多项指标的体内实验证实眼镜蛇毒经腹腔给药,对小鼠腹水型肝癌 H_(22)(HepA)均有明显的抑制作用,其生存时间,癌重生长抑制率接近5-Fu.我们认为眼镜蛇毒是一种新型的,有一定抗癌活性药物,有在临床上进一步研究的价值.     

化学修饰提高胰岛素口服降血糖作用的研究

本文探索了用小分子化合物对胰岛素进行化学修饰,以增加口服降血糖的可能性.制备了乙酰胰岛素、琥珀酰胰岛素和半乳糖酰胰岛素.这些胰岛素不仅较好地保持了天然胰岛素的活性,而且其口服降血糖作用也较天然胰岛素明显增加,其中琥珀酰胰岛素是天然胰岛素的口服降血糖作用的二倍以上.这为口服或肛门给药的胰岛素新剂型的研制提供了科学依据.     

中国种子植物区系定量化研究——Ⅰ区域性种子植物区系研究实用程序工作原理(QX—系列程序)

本文根据吴征镒教授对中国种子植物属分市区类型研究结果,研制出定量化研究区域性种子植物区系的电子计算机程序,应用本程序可完成某区系的分布区类型统计分析,科属组成分析和与其它地区以共有属关系构建的相似性系数的谁知盘中计算,同时可大量节省研究人员的劳动强度和时间,对提高研究水平有一定的效果。     

变形杆菌的耐药性及接合性R质粒的检测

本文报告了从烧伤病人感染创面分离、鉴定的35株变形杆菌的药敏试验及接合性R质粒的检测结果。35株变形杆菌双测试的6种抗菌药物都具有不同程度的耐药性。其中,对6种药物同时耐受的有26株(74.3％)。对其中的27株做了接合试验,接合性R质粒的检出率为70.4%。     

1,25-双羟胆钙化醇及其受体含量检测的实验研究

 建立了一种改良的血清1,25-双羟胆钙化醇(1,25-Dihydroxycholecalciferol,DHCC)超微量放射受体检测(RRA)技术。完成了灵敏度、精密度、准确度、稳定性及特异性等技术指标。报告了我国健康青年血清DHCC正常值;检测了先天性佝偻病、青春期佝偻病病人及患肾性骨病奶牛等血清DHCC水平。 根据配体与受体相互结合的定量关系,建立了DHCCR(DHCC受体)检测技术。在游离与结合配基分离方面,除建立与比较了DCC(葡聚糖包埋的活性炭)及HAP(羟基磷灰石)方法外,还首次将IEF(等电聚焦电泳)应用于DHCCR分离技术。对佝偻病鸡小肠粘膜上皮细胞受体含量进行了检测并比较了鸡小肠、输卵管壳腺及肝组织DHCCR含量。     

Phagocytic cell molecules that bind the collagen-like region of C1q. Involvement in the C1q-mediated enhancement of phagocytosis

C1q binds to and elicits cellular responses by several cell types, including monocytes, macrophages, neutrophils, B cells, and fibroblasts. The cell-binding domain is located within the collagen-like pepsin-resistant region of the C1q molecule (C1q tails). An affinity matrix of C1q tails coupled to Sepharose was used to select C1q-binding proteins from detergent extracts of surface-iodinated human monocytes, polymorphonuclear leukocytes, and the U937 cells. The major radiolabeled polypeptide eluted specifically from the ligand affinity column had an apparent molecular mass (Mr) of 126,000. Minor iodinated components eluted from Sepharose-tails migrated with Mr of 216,000 and 55,000. When subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing conditions no change in the migration of any of these polypeptide bands was detected. None of these polypeptides reacted with antibodies directed against the integrins alpha 5 beta 1 (fibronectin receptor) or alpha v beta 3 (vitronectin receptor), LFA-1, or to several other cell adhesion molecules. The Mr 126,000 band was found to contain more than one polypeptide. Lectin binding properties, susceptibility to glycosidases and proteases, and immunoreactivity with the monoclonal antibody L-10, indicated that CD43 (sialophorin/leukosialin) is a component of this band. However, further data show that a monoclonal antibody, generated by immunization with the isolated Clq-binding fractions, recognizes a cell surface sialoglycoprotein distinct from CD43 and inhibits the C1q-mediated enhancement of phagocytosis in monocytes. These latter observations provide the first definitive connection between a specific phagocytic cell surface protein and a known C1q-mediated function. While these proteins contain sialic acid, binding assays and functional assays using neuraminidase-treated cells demonstrate that the functional interaction between C1q and the cell surface is not via sialic acid. The data taken together indicate either that the functional C1q receptor on phagocytic cells is a multi-subunit complex or that multiple proteins can interact with the fragment of C1q containing the cell-binding domain, at least one of which is involved in the C1q-mediated enhancement of phagocytosis.     

Structural and functional studies of cross-linked Go protein subunits

The guanine nucleotide binding proteins (G proteins) that couple hormone and other receptors to a variety of intracellular effector enzymes and ion channels are heterotrimers of alpha, beta, and gamma subunits. One way to study the interfaces between subunits is to analyze the consequences of chemically cross-linking them. We have used 1,6-bismaleimidohexane (BMH), a homobifunctional cross-linking reagent that reacts with sulfhydryl groups, to cross-link alpha to beta subunits of Go and Gi-1. Two cross-linked products are formed from each G protein with apparent molecular masses of 140 and 122 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Both bands formed from Go reacted with anti-alpha o and anti-beta antibody. The mobility on sodium dodecyl sulfate-polyacrylamide gel electrophoresis is anomalous since the undenatured, cross-linked proteins have the same Stokes radius as the native, uncross-linked alpha beta gamma heterotrimer. Therefore, each cross-linked product contains one alpha and one beta subunit. Activation of Go by guanosine 5'-3-O-(thio)triphosphate (GTP gamma S) does not prevent cross-linking of alpha to beta gamma, consistent with an equilibrium between associated and dissociated subunits even in the presence of GTP gamma S. The same cross-linked products of Go are formed in brain membranes reacted with BMH as are formed in solution, indicating that the residues cross-linked by BMH in the pure protein are accessible when Go is membrane bound. Analysis of tryptic peptides formed from the cross-linked products indicates that the alpha subunit is cross-linked to the 26-kDa carboxyl-terminal portion of the beta subunit. The cross-linked G protein is functional, and its alpha subunit can change conformation upon binding GTP gamma S. GTP gamma S stabilizes alpha o to digestion by trypsin (Winslow, J.W., Van Amsterdam, J.R., and Neer, E.J. (1986) J. Biol. Chem. 261, 7571-7579) and also stabilizes the alpha subunit in the cross-linked product. Cross-linked G o can be ADP-ribosylated by pertussis toxin. This ADP-ribosylation is inhibited by GTP gamma S with a concentration dependence that is indistinguishable from that of the control, uncross-linked G o. These two kinds of experiments indicate that alpha o is able to change its conformation even though it cannot separate completely from beta gamma. Thus, although dissociation of the subunits accompanies activation of G o in solution, it is not obligatory for a conformational change to occur in the alpha subunit.