解毒机对蔬菜中剧毒有机磷农药降解效果的评价

目的 了解解毒机对蔬菜中多种剧毒有机磷农药降解情况.方法 将残留在生菜、上海青、四季豆、黄瓜上的甲胺磷、久效磷、乐果和对硫磷,用解毒机进行清洗,同时用自来水浸泡作对照,然后采用毛细管柱气相色谱法测定,计算降解率,评价其降解效果.结果 解毒机清洗蔬菜20 min达最佳,在4种蔬菜中甲胺磷的降解率为72.13％ ～79.86％,久效磷为74.58％～ 81.99％,乐果为49.33％ ～ 55.08％,对硫磷为57.34％ ～60.03％.自来水浸泡蔬菜30 min达最佳,在4种蔬菜中4种农药的降解率在19.74％ ～35.91％之间.结论 解毒机对蔬菜中剧毒有机磷农药降解速度快,效果好.     

Rescue of CFTR NBD2 mutants N1303K and S1235R is influenced by the functioning of the autophagosome

The missing phenylalanine at position 508, located in nucleotide-binding domain (NBD1) of the cystic fibrosis transmembrane regulator (CFTR), is the most common cystic fibrosis mutation. Severe disease-causing mutations also occur in NBD2. To provide information on potential therapeutic strategies for mutations in NBD2, we used a combination of biochemical, cell biological and electrophysiological approaches and newly created cell lines to study two disease-causing NBD2 mutants, N1303K and S1235R. We observed that neither was sensitive to E64, a cysteine protease inhibitor. However, further investigation showed that when treated with a combination of correctors, C4?+?C18, both mutants also responded to E64. Further exploration to assess aggresome throughput using the autophagy regulator LC3 as a marker showed that, in the absence of correctors, N1303K showed a stalled throughput of LC3-II to the aggresome. The throughput became active again after treatment with the corrector combination C4?+?C18. Confocal microscopic studies showed that the N1303K and S1235R mutant proteins both co-localized with LC3, but this co-localization was abolished by the corrector combination and, to a lesser extent, by VX-809. Both the corrector combination and VX-809 increased the CFTR chloride channel function of both mutants. We conclude that correctors have a dual effect, particularly on N1303K: they improve trafficking and function at the plasma membrane and reduce the association with autophagosomes. After treatment with correctors persistent degradation by the autophagosome may limit restoration of function. Thus, mutations in NBD2 of CFTR, in contrast to ΔF508-CFTR, may require additional personalized strategies to rescue them.     

Immunohistochemical localization of neprilysin in the human cerebral cortex: inverse association with vulnerability to amyloid β-protein (Aβ) deposition

We investigated the immunohistochemical localization of neprilysin, a putative amyloid β-protein (Aβ)-degrading enzyme, in postmortem human brain tissues. In the cerebral cortex, neprilysin immunoreactivity was weak, but relatively dense distribution was found in the primary somatosensory and visual cortices compared with the hippocampus and association cortices. In Alzheimer brain, neprilysin-positive dystrophic neurites occurred in senile plaques in the primary cortices, an observation that supports the relative abundance of neprilysin-positive neuronal processes. A paucity of neprilysin in the hippocampus and association cortices may contribute to the vulnerability of these areas to Aβ deposition.     

酸性可调的聚乳酸-羟基乙酸共聚物微球的制备

目的制备具有酸性自中和能力的聚乳酸-羟基乙酸共聚物[Poly(lactic-co-glycolic acid),PLGA]微球,用于可注射组织工程支架材料或药物释放。方法用二次乳化的方法,将具有缓冲能力的三聚磷酸盐(TPP)包埋于PLGA微球内,制备出PLGA/TPP的复合微球。结果PLGA与TPP以64:1的摩尔比混合时,所制备的PLGA/TPP微球在降解过程中能很好地维持pH值中性,在降解28 d后周围pH值仍为6.93,远高于同样条件下单纯PLGA降解时周围的pH值6.66(P<0.05)。TPP盐颗粒的量对PLGA微球的降解影响很大,当TPP的量增加到12:1时,降解时的酸性要比单纯PLGA微球更为严重,在降解28 d后的pH值低于纯的PLGA微球,仅为6.35(P<0.05)。结论具有缓冲能力的TPP的适量加入,能够有效地调节PLGA微球在降解过程中所产生的酸,从而缓解周围环境pH值下降的问题,但当TPP的量超过一定值时,反而加快PLGA微球的降解。     

应用单细胞凝胶电泳检测大鼠死后脾细胞核DNA降解与死亡时间的关系

目的:探讨应用单细胞凝胶电泳技术(SCGE)检测大鼠死后脾细胞核DNA降解与死亡时间的一般规律,为早期死亡时间的推断提供新的方法。方法:建立大鼠死亡模型,在死后27h内,每隔3h取脾组织样本进行单细胞凝胶电泳,用共聚焦显微镜摄取彗星图像,应用彗星图像分析软件(IMI1.0)进行图像分析,并作统计学分析。结果:大鼠死后,脾细胞在电泳图像上出现了明显的彗星形拖尾,其尾长(TL)、尾矩(TM)在一定的时间范围内(0～15h)随死亡时间的延长而逐渐增大,二者均与死亡时间(PMI)呈现一定的相关回归关系。结果:单细胞凝胶电泳技术可应用于早期死亡时间的推断;彗星图像分析软件为SCGE的结果分析提供了便利。     

固态青霉素钾的降解动力学研究

目的研究不同温度和相对湿度条件下青霉素钾降解的动力学规律。方法在恒温恒湿条件下使青霉素钾降解,定时测定其含量,并对获得的数据进行数学分析。结果青霉素钾的降解反应速率为-dc/dt=k(c0-c B),降解曲线符合c=c0-Bexp(kt) B,速率常数k可表达为k=Aexp(-Ea/RT)exp(mHr),其中活化能Ea=77.26kJ/mol,常数m=0.1159。结论反应速率表达式表述了青霉素钾的降解过程,符合其实际降解规律。     

Endocytosis,trafficking and exocytosis of intact full-length botulinum neurotoxin type a in cultured rat neurons

Botulinum toxin A (BoNT/A) is a potent neurotoxin that acts primarily by silencing synaptic transmission by blocking neurotransmitter release. BoNT/A comprises a light chain (LC/A) intracellular protease and a heavy chain (HC/A) composed of a receptor binding domain (HC_C/A) and a translocation domain (HC_N/A) that mediates cell entry. Following entry into the neuron, the disulphide bond linking the two peptide chains is reduced to release the LC/A. To gain better insight into the trafficking and fate of BoNT/A before dissociation we have used a catalytically inactive, non-toxic full-length BoNT/A(0) mutant. Our data confirm that BoNT/A(0) enters cortical neurons both in an activity-dependent manner and via a pathway dependent on fibroblast growth factor receptor 3 (Fgfr3) signalling. We demonstrate that both dynamin-dependent endocytosis and lipid rafts are involved in BoNT/A internalisation and that full-length BoNT/A(0) traffics to early endosomes. Furthermore, while a proportion of BoNT/A remains stable in neurons for 3 days, BoNT/A degradation is primarily mediated by the proteasome. Finally, we demonstrate that a fraction of the endocytosed full-length BoNT/A(0) is capable of exiting the cell to intoxicate other neurons. Together, our data shed new light on the entry routes, trafficking and degradation of BoNT/A, and confirm that trafficking properties previously described for the isolated HC_C/A receptor binding domain of are also applicable to the intact, full-length toxin.     

In vitro investigation of fracture load and aging resistance of high-speed sintered monolithic tooth-borne zirconia crowns

ObjectivesThe purpose of this study was to evaluate the fit, fracture load and aging resistance of the monolithic zirconia tooth-borne crowns with conventional and high-speed sintering.MethodsThe Y-TZP block was machined and sintered with conventional and high-speed sintering furnace. The marginal and internal gap between the crown and abutment was measured using a microscope and a fit checking material. A total of 28 crowns were further divided into an undegraded and a degraded group. An accelerated aging test was carried out on the degraded group. The crown was cemented and a fracture resistance was tested. X-ray diffraction was used to evaluate the crystalline structure. The data were analyzed with Student’s t-test, and a one-way ANOVA and Tukey’s multiple comparison test.ResultsThere was no significant difference in mean marginal gap between the two groups. The mean internal gap was significantly greater in the speed sintering than in the conventional sintering (P <0.001). The mean fracture load of the conventional sintering crowns was not significantly different from that of speed sintering crowns after aging. The occurrence of monoclinic crystals of degraded crown was significantly higher than that of undegraded crown both in the conventional (P <0.001) and speed-sintering group (P <0.001).ConclusionsIt was concluded that the monolithic zirconia crowns produced by high-speed sintering showed no significant difference in the marginal gap and the fracture load after aging compared to conventional sintering. Therefore, the high-speed sintering seems a valid method of producing tooth-borne monolithic zirconia crowns.