脑缺血/再灌对蒙古沙土鼠海马突触体酪氨酸磷酸化的影响

用蒙古沙土鼠双侧颈总动脉结扎（ＢＣＡＯ）前脑缺血模型,研究缺血／再灌对海马突触体蛋白酪氨酸磷酸休的影响及ＮＭＤＡ受体（ＮＲ）非竞争性拮抗剂氯胺酮（Ｋｅｔａｍｉｎｅ,ＫＴ）、Ｌ－型电压门控钙离子通道（Ｌ－ｔｙｐｅ ｖｏｌｔａｇｅ ｇａｔｅｄｃａｌｃｉｕｍ ｃｈａｎｎｅｌ,Ｌ－型ＶＧＣＣ）拮抗剂硝苯吡啶（ｎｉｆｅｄｉｐｉｎｅ,ＮＤ）及非ＮＲ拮抗６,７－二硝基喹恶啉上卫四（６,７－ｄｉ－ｎｉｔｒｏｐｕ     

Activation of poly(ADP-ribose) polymerase in the rat hippocampus may contribute to cellular recovery following sublethal transient global ischemia

We have investigated the role of poly(ADP-ribose) polymerase (PARP) activation in rat brain in a model of sublethal transient global ischemia. Adult male rats were subjected to 15 min of ischemia with brain temperature reduced to 34 degrees C, followed by 1, 2, 4, 8, 16, 24, and 72 h of reperfusion. PARP mRNA expression was examined in the hippocampus using quantitative RT-PCR, northern blot analysis, and in situ hybridization. Protein expression was assessed using western blot analysis. PARP enzymatic activity was investigated by measuring nuclear [3H]NAD incorporation. The presence of poly(ADP-ribose) polymers was assessed immunocytochemically. Although PARP mRNA and protein expressions were not altered after ischemia, enzymatic activity was increased 4.37-fold at 1 h (p < 0.05 vs. sham) and 1.73-fold (p < 0.05 vs. sham) at 24 h of reperfusion. Immunostaining demonstrated the presence of poly(ADP-ribose) polymers in CA1 neurons. Cellular NAD+ levels were not significantly altered at any time point. Furthermore, systemic administration of 3-aminobenzamide (30 mg/kg), a PARP inhibitor, prevented the increase in PARP activity at 1 and 24 h of reperfusion, significantly decreased the number of surviving neurons in the hippocampal CA1 region 72 h after ischemia (p < 0.01 vs. sham), and increased DNA single-strand breaks assessed as DNA polymerase I-mediated biotin-dATP nick-translation (PANT)-positive cells (p < 0.01 vs. sham). Furthermore, using an in vitro DNA repair assay, 3-aminobenzamide (30 mg/kg) was shown to block DNA base excision repair activity. These data suggest that the activation of PARP, without subsequent NAD+ depletion, following mild transient ischemia may be neuroprotective in the brain.     

II. Structure and specificity of the interaction between the FHA2 domain of Rad53 and phosphotyrosyl peptides

The forkhead-associated (FHA) domain is a protein module found in many proteins involved in cell signaling in response to DNA damage. It has been suggested to bind to pThr sites of its target protein. Recently we have determined the first structure of an FHA domain, FHA2 from the yeast protein Rad53, and demonstrated that FHA2 binds to a pTyr-containing peptide (826)EDI(pY)YLD(832) from Rad9, with a moderate affinity (K(d) ca. 100 microM). We now report the solution structure of the complex of FHA2 bound with this pTyr peptide. The structure shows that the phosphate group of pTyr interacts directly with three arginine residues (605, 617, and 620), and that the leucine residue at the +2 position from the pTyr interacts with a hydrophobic surface on FHA2. The sequence specificity of FHA2 was determined by screening a combinatorial pTyr library. The results clearly show that FHA2 recognizes specific sequences C-terminal to pTyr with the following consensus: XX(pY)N(1)N(2)N(3), where N(1)=Leu, Met, Phe, or Ile, N(2)=Tyr, Phe, Leu, or Met, and N(3)=Phe, Leu, or Met. Two of the selected peptides, GF(pY)LYFIR and DV(pY)FYMIR, bind FHA2 with K(d) values of 1.1 and 5.0 microM, respectively. The results, along with other recent reports, demonstrate that the FHA domain is a new class of phosphoprotein-binding domain, capable of binding both pTyr and pThr sequences.     

基于复杂性度量的心率变异信号非线性分析

假设心率变异信号是累积－发放模型（Ｉｎｔｅｇｒａｔｅ－ｆｉｒｅ）与非线性动力学系统耦合产生的峰电位链（ＳｐｉｋｅＴｒａｉｎ）。以符号动力学为基础,提出利用峰电位间隔（ｉｎｔｅｒｓｐｉｋｅｉｎｔｅｒｖａｌ,ＩＳＩ）及其随机替代数据的Ｃ１、Ｃ２复杂度来定量刻划非线性动力学系统特性。结果表明：确定性驱动产生的峰电位间隔序列可以与随机性驱动产生的峰电位间隔序列区分开。因此,在噪声干扰较强的生理信号中,尤其是在不清楚非线性动力系统变量和峰电位间隔序列之间是否存在微分同胚的情况下,以复杂性度量来代替以Ｔａｋｅｎｓ嵌入定理为基础的关联维数、Ｌｙａｐｎｏｖ指数等描述动力系统特征的方法是合适的。最后通过２类共３７个个体,每个个体的心电数据为１０００个Ｒ－Ｒ间期的微分序列检验心率变异信号的非线性结构。     

蝮蛇抗栓酶伍用低强度He—Ne激光血管内照射治疗脑梗死50例

目的探讨蝮蛇抗栓酶伍用低强度Ｈｅ－Ｎｅ激光血管内照射治疗脑梗死。方法用蝮蛇抗栓酶静滴伍用低强度Ｈｅ－Ｎｅ激光血管内照射（ＩＬＩＢ）治疗一疗程。结果治疗后临床效果明显（总有效率９４．００％）,血流变学值和脑动脉平均血流速度（Ｖｍ）均有显著或非常显著性差异（Ｐ＜０．０５或Ｐ＜０．０１）。结论该方法治疗脑梗死效果满意。     

森林流域土壤饱和渗透系数与有效孔隙度模型的研究

以长白山自然保护区内未受扰动的两种典型原始森林土壤为对象,通过野外选取原状土样,在实验室内测定其饱和渗透系数和有效孔隙度,利用回归分析法分别建立了森林土壤内饱和渗透系数和有效孔隙度随深度变化的数学模型,即Ｋｓ（ｚ）＝Ｋ０－ｆ１ｌｎａ１ｚ和ω（ｚ）＝ω０－ｆ２ｌｎａ２ｚ．将所得出的对数模型与Ｂｅｖｅｎ所提出的指数模型进行比较表明,在森林流域内对数模型不仅适用范围比指数模型广,而且精度明显高于指数模型,它更接近于野外实际情况．     

Biological Reduction of Trichloroethene Supported by Fe(0)

An anaerobic culture reductively transformed trichloroethene (TCE) in an aqueous medium containing elemental iron as the sole electron source. The TCE disappearance rate was enhanced and the product distribution was markedly altered when the culture was present. In abiotic samples containing Fe(0) but no culture, 11 µmol TCE (equivalent to an aqueous concentration of 260 µM) disappeared over a period of 39 days, with ethene and ethane as the major reduction products. Small amounts of cis-dichloroethene (cis-DCE), 1,1-DCE, and vinyl chloride (VC) also were detected. When the culture was incubated with TCE and Fe(0), the same amount of TCE was transformed in less than 2 weeks. The major products after 39 days were VC, ethene, and ethane. VC accounted for 65% of the initial TCE and appeared to be reduced further to ethene at slow rates. The significant VC production in the culture-amended samples indicates that most TCE was transformed microbially rather than chemically. The data indicate that abiotic and biological reduction of chlorinated ethenes can be coupled to enhance treatment efficiency. The results also suggest that microbial dechlorination within and downgradient from iron walls is potentially important for evaluating the long-term performance of permeable iron barriers.     

人造血干/祖细胞多态性的研究:Ⅺ.人正常骨髓CD34~ 造血细胞周期动力学相关大分子DNA、RNA和PRO含量的分析

DNA、RNA和PRO的合成、积累及相互关系是调控细胞周期动力学最主要的三个参数。同时检测这些组成部分能够更精确细致地评判细胞的周期动力学特征。本文探索了人正常骨髓CD34~ 造血细胞周期动力学相关大分子DNA、RNA和PRO的含量,以便认识CD34~ 造血细胞周期动力学的特征。用新型CIMS-100免疫磁性分离系统高效富集人骨髓CD34~ 造血细胞,经FCM及APAAP鉴定,富集的CD34~ 造血细胞的纯度达90～95%。随之采用碘化丙啶(PI)、派若宁Y(PY)及异硫氰荧光素(FITC)分别进行标记DNA、RNA和PRO并在FCM上检测。结果表明,DNA、RNA和PRO在CD34~ 造血细胞中的含量明显低于单个核细胞,分别仅占后者的34±3%、48±21%及62±14%。结合我们以往的结果,我们认为CD34~ 造血细胞的确是一独特的体细胞群,不仅表现在重建造血与免疫学功能上,而且表现在细胞周期动力学上。据我们所知,这是目前国际上首次有关人CD34~ 造血细胞周期动力学相关大分子的系统分析报道,提供了大多数CD34~ 造血细胞处于静止期的直接证据。     

A covalent two-step immobilization technique using itaconic anhydride

β-Glucosidase from almonds (EC 3.2.1.21) was covalently immobilized by a two-step technique. In the first step, double bonds were introduced into the β-glucosidase by derivatization with itaconic anhydride. In separate studies with α-N-protected l-amino acids, it was established that itaconic anhydride acylated mainly primary amino groups of lysines and, to a much lesser extent hydroxyl groups of tyrosines and sulfhydryl groups of cysteines. The acylated β-glucosidase showed no loss of activity and the K _m decreased from 3.6 mM to 2.6 mM when p-nitrophenyl β-d-glucopyranoside was used as the substrate. In the second step, the derivatized β-glucosidase was co-polymerized radically with N,N′-methylenebisacrylamide in buffer solution. The resulting acrylamide immobilizate possessed a much better storage stability at 30–56 °C when compared to β-glucosidase immobilized on Eupergit C. However, the specific activity was higher with the Eupergit immobilizate. Free and acrylamide-immobilized β-glucosidase were used for glucosylation of chloramphenicol by transglucosylation in 20% (v/v) acetonitrile at 37 °C. The acrylamide immobilizate demonstrated a great enhancement of stability and approximately 50% more chloramphenicol β-glucoside was obtained after 5 h. Received: 22 September 1997 / Accepted: 28 October 1997