Leucyl-β-naphthylamide-splitting enzymes in the mammalian endocrine pancreas

The proteolytic capacity of the endocrine pancreas in obese-hyperglycaemic mice was evaluated by using the chromogenic substrate l-leucyl-beta-naphthylamide (LNA). The analytical sensitivity obtained with this substrate in photometric and fluorimetric assays permitted quantitative determinations of C-N-bond-splitting activity in both crude islet homogenates and electrophoretic fractions thereof. The following observations were made: (1) The rate of LNA cleavage was maximal at about pH7 in islets as well as in acinar tissue. An apparent K(m) of 4x10(-5)-6x10(-5)m was calculated for both the endocrine and exocrine pancreas. (2) The level of LNA-splitting enzyme activity was of the same magnitude in the islets as in the liver, and significantly higher in the islets than in the exocrine pancreas. Starving the animals for 7 days did not affect the enzyme activity levels. (3) Two distinct LNA-splitting enzymes could be separated from the pancreatic islets by means of disc electrophoresis, the most rapidly migrating band representing the highest activity. Though similar electrophoresis patterns were obtained with acinar tissue and liver, only one enzyme could be demonstrated in serum. The data suggest that the beta-cells, in addition to being highly specialized for the production of a specific protein, contain a comparatively high capacity for protein catabolism.     

The variability of critical species ofLotus L. in Iran and in the neighbouring countries II

The paper deals with some problems of distribution and variability of the speciesL. angustissimus L.,L. halophilus Boiss. etSprun.,L. laricus Rech. fil.,Aellen etEsfandiari, L.,schimperi Steud.,L. compactus Chrtková-?ertová,L. garcinii DC.     

The variability of critical species ofLotus L. in Iran and in the neighbouring countries I. the circle ofL. corniculatus L. andL. gebelia Vent.

The region of Iran, Iraq, Afghanistan and the neighbouring countries is important for some groups of the speciesLotus L., especially those of the circle ofL. corniculatus L. andL. gebelia Vent. The first group is represented by the speciesL. corniculatus L. with 4 subspecies (3 of which are important for this region), andL. tenuis Waldst. etKit. which here attains the eastern boundary of the continuous area of distribution, and by the eastern speciesL. krylovii Schischk. etSerg. andL. rechingeri Chrtková-?ertová. The second group is represented by the speciesL. gebelia Vent.,L. michauxianus Ser. in DC. andL. libanoticus Boiss. their areas of distribution covering mostly those regions. Most of the species show considerable variability within the species.     

The distribution ofVicia cassubica in Czechoslovakia

Vicia cassubica L. in Czechoslovakia belongs to the characteristic species of light decidous forests, especially oak forests, and of their edges, predominantly in the range of the Pannonian flora and in the adjacent regions.V. cassubica appears little variable both in Czechoslovakia and in its total distribution area.     

Novel dioxomolybdenum(VI) and oxomolybdenum(V) complexes with pyridoxal thiosemicarbazone ligands: Synthesis and structural characterisation

New molybdenum complexes were prepared by the reaction of [Mo^VIO₂(acac)₂] or (NH₄)₂[Mo^VOCl₅] with different N-substituted pyridoxal thiosemicarbazone ligands (H₂L¹ = pyridoxal 4-phenylthiosemicarbazone; H₂L² = pyridoxal 4-methylthiosemicarbazone, H₂L³ = pyridoxal thiosemicarbazone). The investigation of monomeric [MoO₂L¹(CH₃OH)] or polymeric [MoO₂L^1-3] molybdenum(VI) complexes revealed that molybdenum is coordinated with a tridentate doubly-deprotonated ligand. In the oxomolybdenum(V) complexes [MoOCl₂(HL^1-3)] the pyridoxal thiosemicarbazonato ligands are tridentate mono-deprotonated. Crystal and molecular structures of molybdenum(VI) [MoO₂L¹(CH₃OH)]·CH₃OH, and molybdenum(V) complexes [MoOCl₂(HL¹)]·C₂H₅OH, as well as of the pyridoxal thiosemicarbazone ligand methanol solvate H₂L³·MeOH, were determined by the single crystal X-ray diffraction method.     

基于小波和BP网络的视觉诱发电位分类识别

提出了小波分解与BP网络相结合的方法来识别视觉诱发电位（Visual Evoked Potential,VEP）。先用小波分解对VEP进行特征提取和降维。然后用BP网络进行分类识别。     

阿维菌素的研究进展

阿维菌素作为一种占主导地位的生物农药具备一般生物农药的特点,并且它的化学结构新颖,作用机制独特,杀虫活性强,杀虫谱广,但是药效慢、杀虫谱相对较窄、稳定性差和生产成本高则是其明显的缺点。该文主要从阿维菌素B1提取的研究、发酵培养基的研究、高产菌株的选育的研究这三个方面对阿维菌素目前研究的成果及其存在的问题进行了详细的阐述,并对其未来一段时间内的研究前景进行了展望。参考文献18篇。     

分子生物学技术在植物内生菌分类鉴定中的应用

植物内生菌作为微生物中的一个研究领域,近年来一直备受关注。不仅是因为内生菌在农牧业生产和环境净化方面应用的良好表现,而且还为新药研制提供了新的途径。与此同时,植物内生菌分类鉴定的研究也有一定的进展,特别是在分子生物学技术应用到其中后。基于这点,就最近10年来有关植物内生菌分类鉴定的文献所使用的技术进行了分析和讨论。     

A-NK细胞联合IL-2，IL-12在肿瘤免疫治疗中的作用

本文对A-NK细胞联合IL-2和IL-12在抗肿瘤免疫治疗中的作用进行了论述。强调联合应用可高效激活A-NK细胞,提高对肿瘤细胞的杀伤活性。减少IL-2和IL-12的用量及副作用,提高疗效。     

余弦形负载超声变幅杆的设计与研究

研究余弦形负载超声变幅杆特性.求解了加负载时四种超声变幅杆的输入阻抗,得到加负载时输入阻抗和Mbius变换参数的统一算式.当变幅杆的输入抗分量为零时,计算了余弦形负载变幅杆的纵向振动共振频率方程和放大系数.由输入阻抗的表达式讨论了此类变幅杆的工作稳定性条件和相对阻抗相等点.结果表明由两种方法计算的共振频率方程是相同的;余弦形变幅杆的各种参量和方程与负载阻抗紧密相关;有负载力阻时1/4波长变幅杆的放大系数要比1/2波长变幅杆显著的多,和杆两端特性阻抗的几何平均值成正比,而与负载力组成反比.