电离辐射后大鼠离体胰腺腺泡淀粉酶释放及M受体数量变化

我们曾观察到大鼠经γ-射线照射后胰淀粉酶活性降低和分泌减少[1],为进一步探讨照射后胰酶分泌减少的机制,本研究制备出分散的大鼠胰腺腺泡悬液并以不同浓度的~3H-二苯羟乙酸-3-喹咛环酯(~3Hquinuclidinyll benzilatc,简称~3H-QNB)进行M受体结合测定,同时观察胆碱能介质氨甲酰胆碱刺激腺泡所引起的淀粉酶释放反应。结果表明,γ-射线10Gy照射后3天,大鼠分散的胰腺腺泡在氨甲酰胆碱刺激时淀粉酶释放量减少到对照的50％,腺泡M受体与~3H-QNB最大结合量(Bmax)减少到对照的38％,伋M受体与~3H-QNB结合的解离常数(K_D)无改变,说明胰腺腺泡细胞M受体数量的减少可能是照射后胰腺腺泡分泌淀粉酶减少的原因之一。     

射击过程中主要生理特征的研究

八名射击运动员(手枪2人,步枪6人),在实弹射击训练中,连续同步地记录了脑电、心电、心率、阻抗呼吸波。同时记录了受试者持枪稳定的程度。 分析表明,射击环数是五项独立无关的指标综合作用的结果。本文首次对射击时生理指标和射击环数进行系统辨识建模分析,求出每个人的系统参数_i值。找出了每人射击时最佳生理参数,为指导射击练习和反馈训练,提供了客观生理依据。 本文设计的激光光点录相方法,可反映持枪稳定的程度,简单、方便,可在射击训练中采用。     

+G_z暴露时,家兔心率和心水平动脉压关系的研究

在动物离心机上测定了7只轻度麻醉家免暴露于+G_Z时心、眼水平动脉压和心率的变化。+G_Z作用5-12s时、心水平动脉压(HABP)降至最低水平,然后开始代偿性回升。当+G_Z增大到一定值时,于加速度达峰值后,HABP降为0 mmHg、并在峰值后5.5±1.7s降到最大负值,继之代偿性升为正值,并常再度降为负值。我们称HABP的这种变化状态为“临界状态”。+G_Z暴露时,心率以两种型式发生改变:第一种,随着G值增大,心率发生不同程度增快,当加速度达某一G值时,心率突然减慢至2次/秒左右;第二种,当G值≥3时,在暴露过程中,心率逐渐减慢,并在某一G值,心率减慢到2次/秒左右。心率和HABP关系密切。当HABP达临界状态时,心率减慢至2次/秒左右并出现明显节律不整。以心率减慢到2次/秒左右作为家免+G_Z耐力终点是合适的,该指标规律性强,重复性好,实验方法对动物无损伤又易实施。按此标准,测得7只家免的+G_Z耐力为4.85±0.47G。     

TPA对原代白血病细胞的诱导分化作用

本文报告了TPA对32例不同类型白血病细胞的体外分化诱导结果。TPA(1.6×10~-7M)可诱导急性非淋巴细胞(ANLL)白血病细胞迅速出现单核巨噬细胞分化标志:细胞贴壁、胞浆丝状伪足形成,具有类似巨噬细胞的形态改变及相应的细胞化学反应特征。急性淋巴细胞白血病(ALL)和桨细胞白血病(PCL)细胞不发生上述变化,表现为细胞聚集成闭现象。慢性淋巴细胞白血病(CLL)出现桨细胞样形态转化。初发与复发病例的诱导反应相类似。TPA体外诱导分化实验,有助于了解病人白血病细胞的分化潜能,对于鉴别粒单系和淋巴系两类白血病,尤其对于用常规方法分型困难的低分化白血病有一定的临床诊断意义。     

Characterization of cloned chicken anemia virus DNA that contains all elements for the infectious replication cycle.

Circular double-stranded replication intermediates were identified in low-molecular-weight DNA of cells of the avian leukemia virus-induced lymphoblastoid cell line 1104-X-5 infected with chicken anemia virus (CAV). To characterize the genome of CAV, we cloned linearized CAV DNA into the vector pIC20H. Transfection of the circularized cloned insert into chicken cell lines caused a cytopathogenic effect, which was arrested when a chicken serum with neutralizing antibodies directed against CAV was added. Chickens inoculated at 1 day of age with CAV collected from cell lines transfected with cloned CAV DNA developed clinical signs of CAV. The 2,319-bp cloned CAV DNA contained all the genetic information needed for the complete replication cycle of CAV. The CAV DNA sequence has three partially overlapping major reading frames coding for putative peptides of 51.6, 24.0, and 13.6 kDa. The CAV genome probably contains only one promoter region and only one poly(A) addition signal. Southern blot analysis using oligomers derived from the CAV DNA sequence showed that infected cells contained double- and single-stranded CAV DNAs, whereas purified virus contained only the minus strand. It is the first time that the genome of one of the three known single-stranded circular DNA viruses has been completely analyzed.     

Principles of environmental physics

Book Review

Principles of environmental physicsJ.L. Monteith and M.H. Unsworth Second edition. London: Edward Arnold, 1990. xii + 291 pages. £30.00 (hardback), £14.95 (paperback). ISBN 0-7131-2931-X     

Lectin binding sites on head structures of the spermatid and spermatozoon of the mosquito Culex quinquefasciatus (Diptera,Culicidae)

The presence of intranuclear and acrosomal lectin binding sites in spermatids and spermatozoa of the mosquito Culex quinquefasciatus was analysed. Direct and indirect lectin-gold techniques were used on LR White-embedded cells. The nuclear compartment was the structure most intensely labelled. Early spermatid nucleus showed moderate labelling for peanut agglutinin (PNA), Griffonia simplicifolia IB4 (GS-IB4) and Ricinus communis agglutinin (RCA), and light labelling for the other lectins tested. The sperm nucleus was intensely labelled by all lectins. The acrosome, an enzyme-containing structure, was labelled by some lectins. The anterior acrosomal region was labelled by PNA, while the proximal acrosomal region was labelled by PNA and G. simplicifolia II (GS II) lectins, and showed the presence of fucose residues with the use of Ulex europaeus I (UEA-I) lectin. The spermatozoa stored in the spermatheca showed the same pattern of labelling as that observed in spermatozoa localized in testis and seminal vesicles for all lectins tested. Carbohydrate residues in the nuclear compartment may be involved with the process of chromatin condensation. In the acrosomal region these residues may play a role in the process of spermoocyte interaction.     

Prohibitin, an evolutionarily conserved intracellular protein that blocks DNA synthesis in normal fibroblasts and HeLa cells.

Genes that act inside the cell to negatively regulate proliferation are of great interest because of their implications for such processes as development and cancer, but these genes have been difficult to clone. This report details the cloning and analysis of cDNA for prohibitin, a novel mammalian antiproliferative protein. Microinjection of synthetic prohibitin mRNA blocks entry into S phase in both normal fibroblasts and HeLa cells. Microinjection of an antisense oligonucleotide stimulates entry into S phase. By sequence comparison, the prohibitin gene appears to be the mammalian analog of Cc, a Drosophila gene that is vital for normal development.     

Characterization of recombinant human renin: Kinetics,pH-stability, and peptidomimetic inhibitor binding

The kinetic behavior andpH-stability of recombinant human renin was analyzed using a new fluorogenic substrate based on the normal P₆-P₃ renin cleavage sequence in human angiotensinogen. The design of this fluorogenic substrate makes possible, for the first time, direct monitoring of the kinetics of proteolytic conversion of prorenin to renin. ThepH-stability profile for renin, measured with the substrate at 25°C, indicated a broad plateau of stability betweenpH 6.0 and 10.0. Analysis of thepH-activity profile of renin for the substrate indicated a minimumK _m (1.8 µM) atpH 7.4 and a maximumV _m betweenpH 7.4 and 8.0. The thermodynamics of the binding of a novel, soluble, peptidomimetic inhibitor to renin indicated it is possible to retain the tight-binding characteristics and enthalpy contributions to binding of larger peptide-derived inhibitors, while reducing inhibitor size and entropic contributions to binding. A novel derivative of the fluorogenic substrate, containing a 3-methyl histidine substitution at the P₂ site, was used to test the recent hypothesis that renin functions by virtue of substrate-directed catalysis.