乙型肝炎流行病学数学模型

本文根据乙型肝炎的自然传播过程,建立由偏微分方程表达的数学模型．模型中所有参数都由实际资料估计所得,而且考虑了乙型肝炎感染与转归随年龄变化的特点．免疫接种前、后模型模拟的结果与实际观察值相符,这说明模型能够反映乙型肝炎在人群中的传播过程．     

血管内照射（He－Ne）对患者外周血淋巴细胞中凋亡细胞（PCD）的影响

本文报道了用氦氖激光血管内照射（ＩＬＩＢ）治疗九例患者过程中,应用流式细胞仪检测外周血淋巴细胞中凋亡细胞的发生,结果提示,照射后凋亡细胞百分率为（６．４３±５．０７％）与照射前比较（０．３８±０．５３％）,ｐ＜０．０５。     

叠氮钠对大鼠学生记忆及海马和额叶皮层内Aβ的影响

目的：观察大鼠长期皮下注射叠氮钠后的学习记忆、中枢神经系统β－淀粉样蛋白含量的改变。方法：采用Morris水迷宫、放射免疫和透射电镜的方法。结果：大鼠出现明显的空间记忆功能障碍,海马和额叶大脑皮层内Aβ含量升高。结论：长期皮下注射叠氮钠可以制备AD模型,并导致中枢Aβ的升高。     

The structure analysis and antigenicity study of the N protein of SARS-CoV

The Coronaviridae family is characterized by a nucleocapsid that is composed of the genome RNA molecule in combination with the nucleoprotein (N protein) within a virion. The most striking physiochemical feature of the N protein of SARS-CoV is that it is a typical basic protein with a high predicted pI and high hydrophilicity, which is consistent with its function of binding to the ribophosphate backbone of the RNA molecule. The predicted high extent of phosphorylation of the N protein on multiple candidate phosphorylation sites demonstrates that it would be related to important functions, such as RNA-binding and localization to the nucleolus of host cells. Subsequent study shows that there is an SR-rich region in the N protein and this region might be involved in the protein-protein interaction. The abundant antigenic sites predicted in the N protein, as well as experimental evidence with synthesized polypeptides, indicate that the N protein is one of the major antigens of the SARS-CoV. Compared with o     

Overexpression of TaHSF3 in Transgenic Arabidopsis Enhances Tolerance to Extreme Temperatures

Heat shock factors (HSFs) in plants regulate heat stress response by mediating expression of a set of heat shock protein (HSP) genes. In the present study, we isolated a novel heat shock gene, TaHSF3, encoding a protein of 315 amino acids in wheat. Phylogenetic analysis showed that TaHSF3 belonged to HSF class B2. Subcellular localization analysis indicated that TaHSF3 localized in nuclei. TaHSF3 was highly expressed in wheat spikes and showed intermediate expression levels in roots, stems, and leaves under normal conditions. It was highly upregulated in wheat seedlings by heat and cold and to a lesser extent by drought and NaCl and ABA treatments. Overexpression of TaHSF3 in Arabidopsis enhanced tolerance to extreme temperatures. Frequency of survival of three TaHSF3 transgenic Arabidopsis lines was 75–91 % after heat treatment and 85–95 % after freezing treatment compared to 25 and 10 %, respectively, in wild-type plants (WT). Leaf chlorophyll contents of the transformants were higher (0.52–0.67 mg/g) than WT (0.35 mg/g) after heat treatment, and the relative electrical conductivities of the transformants after freezing treatment were lower (from 17.56 to 18.6 %) than those of WT (37.5 %). The TaHSF3 gene from wheat therefore confers tolerance to extreme temperatures in transgenic Arabidopsis by activating HSPs, such as HSP70.     

NMR measurements of Ca2+ and H+ transport mediated by A23187 and reconstituted plasma membrane Ca2+-ATPase

NMR-based assays for measuring the fluxes of Ca²⁺, H⁺, and ATP in liposomal systems are presented. The ¹⁹F NMR Ca²⁺-chelating molecule 5,5-difluoro-1,2-bis(o-amino-phenoxy)ethane-N,N,N′,N′-tetraacetic acid (5FBAPTA) was trapped inside large unilamellar vesicles and used to monitor passive and A23187-mediated Ca²⁺ transport into them. The data were analyzed using progress curves of the transport reaction. They demonstrated the general applicability of 5FBAPTA as a ¹⁹F NMR probe of active Ca²⁺ transport. ³¹P NMR time-courses were used to monitor simultaneously the ATP hydrolysing activity of the reconstituted human erythrocyte Ca²⁺-ATPase and the concomitant acidification of the reaction medium in a suspension of small unilamellar vesicles. Using an estimate of the extraliposomal buffering capacity, the H⁺/ATP coupling stoichiometry, in the presence of A23187, was estimated from the NMR-derived data at steady state; it amounted to 1.4±0.3. This result is discussed with respect to the issue of molecular `slip' in the context of a non-equilibrium thermodynamics model of the pump (accompanying paper in this issue). Importantly, NMR, in contrast to optical detection methods, can potentially register all fluxes and (electro)chemical gradients involved in the Ca²⁺-ATPase-mediated H⁺/Ca²⁺counterport, in a single experiment. Received: 19 June 1997 / Accepted: 3 December 1997     

Isolation and molecular analysis of genes Stpk-V2 and Stpk-V3 homologous to powdery mildew resistance gene Stpk-V in a Dasypyrum villosum accession and its derivatives

Wheat-Dasypyrum villosum translocated chromosomes T6V#2S?6AL and T6V#4S?6DL are known to confer excellent resistance to wheat powdery mildew (PM). However, it is difficult to distinguish the two sources of PM resistance genes through multi-pathotype testing because to date no virulence for them has been found. To reveal the relationship between the PM resistance genes from the two translocations, the sequence of the Stpk-V gene, a key member of powdery mildew resistance locus Pm21, was used as a reference to isolate homologous genes from a D. villosum accession No.1026 and its derivatives 6V#4(6D) disomic substitution (DS) line RW15 and T6V#4S?6DL translocation line Pm97033. Two genes Stpk-V2 and Stpk-V3 were cloned from No.1026. Sequence alignment showed that Stpk-V2 and Stpk-V3 shared 98.2 % and 96.2 % of their DNA and 99.3 % and 100 % of their amino acids in identity with Stpk-V. Compared with Stpk-V, a 22-bp direct sequence repeat and a miniature inverted-repeat transposable element (MITE) were found in the intron 4 of Stpk-V2 and Stpk-V3, respectively. However, Stpk-V2 was not present in DS line RW15 and translocation line Pm97033 based on the PCR result, indicating that Stpk-V2 did not contribute to the PM resistance of RW15 and Pm97033. In the promoter region, a 78-bp insertion was found not only in Stpk-V2 and Stpk-V3, but also in its orthologous gene Stpk-A of wheat. In addition, there was a 17 bp/8 bp deletion/insertion in the putative promoter of Stpk-V3 in comparison with that of Stpk-V/Stpk-V2. Real-time quantitative RT-PCR analysis indicated that the expression levels of Stpk-V and Stpk-V3 genes in the translocation lines were induced by the pathogen, but Stpk-V had a higher expression level than Stpk-V3 at 12 h after inoculation with Bgt. The diversity of Stpk-V gene will help to explore new resistance genes to PM in D. villosum for wheat breeding.