一种纯化细菌有机磷水解酶的简便方法

Cibacron blue T_3GA与溴化氰活化的Sepharose 4B偶联后,产生一种能有效地分离有机磷水解酶的吸附剂。用0.15mol/L MgCl_2溶液从黄杆菌P3—2细胞抽提出的粗酶液通过柱层析分离,即可得到纯化8倍、酶活性回收率为269.4％的纯酶制品。该酶制品用凝胶电泳测是均一的。     

固定化酶的微环境效应—载体离子基团性质的影响

作者合成了阴离子型和阳离子型葡聚糖,以此为载体,用CNBr活化其剩余羟基,固定化了葡萄糖淀粉酶和葡萄糖异构酶。就离子型载体对固定化酶的蛋白载量、最适pH和热稳定性等的影响做了考察。发现固定化酶的蛋白载量不仅与载体的电性质有关,也与酶分子自身的电性质有关。当载体电性质与酶蛋白电性质相反时,固定化酶的蛋白载量增加,热稳定性提高、载体电性质与酶蛋白电性质相同时,固定化酶的蛋白载量不变或下降,其热稳定性不变。作者还发现当离子型载体孔度和体系缓冲液浓度一定时,酶分子能否进入多孔性载体内部,对其最适pH是否变化影响极大。若酶分子仅被连接在载体的外表层,其最适pH不发生变化,反之亦然。作者还观察到当多糖类载体引入氨基或羧基后,大大增强了其抵抗微生物侵蚀的能力。     

从二溴百里香醌的抑制效应分析融合膜电子传递的途径

甲基紫精(MV)系统中,在对类囊体膜的光合磷酸化(PSP)活力近于完全抑制的二溴百里香醌(DBMIB)浓度下,由类囊体残缺膜与线粒体嵴膜组成的融合膜PSP活力不仅不被抑制,反而受到不同程度的促进。在铁氰化钾(FeCy)系统中,DBMIB对类囊体膜的PSP活力不能完全抑制,同样浓度的DBMIB对融合膜的PSP活力有抑制效应。检测了不同膜在不同系统中,光下耗氧、放氧、FeCy还原和融合效应的关系等,论证了融合膜中电子传递的途径。     

脑室注射6-羟多巴胺对黄鼠冬眠入眠的影响

采用脑室内注射化学去交感药物6-羟多巴胺(6-OHDA)的方法,观察了人为地降低脑内去甲肾上腺素(NE)系统活动对达乌尔黄鼠入眠的影响。结果表明:脑室注射100-200μg6-OHDA使脑内NE含量减少50％以上,明显促进黄鼠入眠,平均入眠诱导期比自然冬眠动物明显缩短,整个冬眠季内冬眠时间延长,冬眠黄鼠仍具有正常的入眠觉醒周期。这些结果提示脑内NE系统活动水平降低是触发动物入眠的重要因素之一。     

A genetic linkage map of 96 loci on the short arm of human chromosome 3.

We constructed a genetic map of 96 loci on the short arm of human chromosome 3 (3p) in 59 families provided by the Centre d'Etude du Polymorphisme Humaine (CEPH). Twenty-nine continuously linked loci were placed on the map with likelihood support of at least 1000:1; one locus, D3S213, was placed on the map with likelihood support of 871:1; D3Z1, an alpha satellite centromeric repeat probe, was placed on the map with likelihood support of 159:1; 65 loci were assigned regional locations. The average heterozygosity of the uniquely ordered markers was 49%. The map extends from 3p26, the terminal band of 3p, to the centromere (from D3S211 to D3Z1). Multipoint linkage analysis indicated that the male, female, and sex-averaged maps extend for 102, 147, and 116 cM, respectively. The mean genetic distance between uniquely ordered loci on the sex-averaged map was 4.0 cM. Probe density was greatest for the region of 3p between D3F15S2e and the telomere. The sex-averaged map contained two intervals greater than 10 cM. Seventeen probes were localized by fluorescence in situ hybridization. The loci described in this report will be useful in building an integrated genetic and physical map of this chromosome.     

Localized membrane depolarizations and localized calcium influx during electric field-guided neurite growth.

Our study explores the mechanisms behind neurite galvanotropism. Using phase, differential interference contrast and ratiometric fluorescence microscopy, we reveal four responses of N1E-115 mouse neuroblastoma cells to 0.1-1.0 mV/microns uniform DC electric fields: cathode-directed neurite initiation and elongation, cathode-biased growth cone filopodial protrusions, transient cathode-localized calcium increases, and persistent cathode-localized membrane depolarizations. These newly demonstrated events are temporally and spatially correlated, suggesting that they are causally related. The calcium increases are prevented by calcium channel blockers and by the removal of extracellular calcium. We therefore propose that the observed field-induced membrane depolarizations activate voltage-dependent calcium channels, resulting in cathode-localized calcium influx. This, in turn, may initiate the observed cathode-biased growth cone filopodial protrusions, followed by the cathode-directed neurite elongation.     

Simultaneous bilateral forearm revascularization

A successful simultaneous bilateral forearm revascularization was performed on a 17-year-old boy. Functional recovery of both forearms was evaluated 42 months after injury. The patient can use both hands for the activities of daily living. So far, he has been employed and has no significant psychological problems. Temporary intraluminal silicone shunts are extremely helpful for reducing ischemic damage to the injured limb. The sufficient skeletal shortening of the upper limb replantation is crucially important. The wounds must be managed by aggressive and repeated debridement. Accurate primary nerve repair is essential, and the early postoperative rehabilitation is also important to achieve a satisfactory functional return. The functional replanted or revascularized upper extremity is superior to an amputation or prosthesis, especially in the cases of bilateral upper extremity amputation or devascularization.     

Changes in pulmonary Cu−Zn contents in superior mesenteric artery occlusion shock of rabbit

Contents of Cu and Zn of into-pulmonary blood (IPB), out-pulmonary blood (OPB), Lung tissue, and supernatant and macrophages of Lung Lavage were determined in superior mesenteric artery occlusion (SMAO) shock of rabbits. Zn of pulmonary tissue was 11.42 +/- 0.60 and 14.52 +/- 1.78 (micrograms/g wet wt) in SMAO shock and control groups, respectively. Content of Zn was found to be lower, Cu was not changed, and Cu/Zn ratio increased in lung tissue in SMAO shock. Contents of Cu and Zn in other samples were not changed. The results suggest that lower Zn in lung tissue related to acute lung injury.     

On-line thermal monitoring of aspartic acid separation in a high voidage ion-exchange column at high flow rate

A simple thermal monitoring technique has been successfully applied to an adsorption system using a novel ion exchanger with a large internal void volume (voidage) which can be operated at high superficial velocity (SV). Temperature changes resulting from heats of adsorption could be followed effectively using semi-conductor thermistor devices inserted into the resin through the column wall. Results show that, despite the high feed rates adopted, the thermal signals generated can be consistently related to the position of the breakthrough front within the bed.