Creatol (5-hydroxycreatinine), a new toxin candidate in uremic patients

Summary Both 5-hydroxy-1-methylhydantoin (3) and the hitherto unrecognized 5-hydroxycreatinine (2-amino-5-hydroxy-1-methyl-imidazol-4(5H)-one or creatol) (6) can be isolated from the urine of uremic patients, in whom these compounds probably arise as oxidative metabolites of creatinine (1). The enhanced production of the well-known uremic toxin, methylguanidine (8), from creatinine (1) in such patients, almost certainly occurs via the newly recognized metabolite (6).     

AS—3毒素的分离纯化及理化性质研究

ＡＳ－３毒素是由作者分离鉴定的一株梭关芽孢杆菌产生的神经性毒素，是一种大分子蛋白质。作者对ＡＳ－３毒素的分离纯化及理化性质作了初步研究，测得其蛋白质分子由两个亚基组成，分子量为１４８０００Ｄａ，等电点为５．９６，最大吸收波长２８８．５ｎｍ，含１７种氨基酸，二级结构中α－螺旋占多数，β－折迭和无规则卷曲较少。     

Effects of pertussis toxin onα 1-agonist-mediated phosphatidylinositide turnover and myocardial cell hypertrophy in neonatal rat ventricular myocytes

Summary In neonatal rat ventricular myocytes pretreatment with pertussis toxin did not affect 1 M (–)-norepinephrine stimulation of inositol phosphates or myocardial cell hypertrophy as measured either by protein radiolabelling or by myocardial cell protein content. Thus guanine nucleotide protein (s) ADP-ribosylated by pertussis toxin do not play a role in two ₁-adrenoceptor-mediated processes, phosphatidylinositide turnover and induction of myocardial cell hypertrophy.     

产毒素大肠杆菌LTB-K99融合基因的构建

利用PCR技术从原始菌种中扩增得到K99和LTB基因,将K99和LTB基因连接起来,构建了LTB-K99融合基因.融合基因克隆到pBS-T载体上,转化大肠杆菌top10,经Bam HI和Xho I双酶切鉴定重组质粒.测序分析结果表明,该融合基因有正确的阅读框,为以后转入表达载体的构建奠定了基础.     

粘膜佐剂霍乱毒素B亚单位的克隆与表达

目的 :构建表达粘膜佐剂霍乱毒素B亚单位 (CTB)基因的重组质粒 ,并在大肠杆菌中表达获得基因重组蛋白。方法 :用PCR方法从霍乱弧菌中扩增CTB片段 ,将其转入原核载体质粒pET-32a( ) ,在大肠杆菌Top10克隆 ,并在BL21中表达。结果 :重组质粒PET-CTB的全长序列经分析与基因文库公布的一致 ;表达蛋白经SDS-PAGE分析 ,相对分子量与文献相符 ;重组蛋白竟Westernblot检测有抗原性。结论 :基因重组菌表达的CTB蛋白可能作为有效、安全的粘膜佐剂用于口服疫苗的研制     

眼镜蛇膜毒素与单克隆抗体偶联物对鼻咽癌细胞的特异性杀伤作用

应用柱层析和凝胶过滤的方法,从中华眼镜蛇的粗毒中分离纯化出一个不含磷脂酶Ａ２（ＰＬＡ２）的膜毒素（Ｍｅｍｂｒａｎｅｔｏｘｉｎ,ＭＴ）组分．ＭＴ经电泳鉴定为单一成分．将ｑｄＭＴ与鼠抗人鼻咽癌细胞（ＣＮＥ２）的单克隆抗体（ＢＡＣ５）偶联制备成免疫毒素（ＢＡＣ５－ＭＴ）,经间接免疫荧光检测,证实免疫毒素仍保留了很好的生物活性．体外抗癌实验证明,在无Ｃａ２＋培养基中,游离的ＭＴ对ＣＮＥ２和Ｓ１８０细胞均有快速杀伤作用,并且对２种细胞的杀伤作用没有明显的区别,但ＢＡＣ５－ＭＴ同样在无Ｃａ２＋条件下,仅对靶细胞ＣＮＥ２有强烈的杀伤作用（杀伤率达７８．６％）,对Ｓ１８０细胞只有很弱的杀伤作用（杀伤率为２１．３％）．结果表明ＢＡＣ５－ＭＴ对ＣＮＥ２细胞有很好的选择性杀伤作用,提示蛇膜毒素在肿瘤的导向治疗中将是一条很有希望的途径．     

Integration and inheritance stability of foreignBt toxin gene in the bivalent insect-resistant transgenic cotton plants

Genetic and expressional stability of Bt toxin gene is crucial for the breeding of insect-resistant transgenic cotton varieties and their commercialization. Genomic Southern blot analysis of R₃, R₄ and R₅ generations of bivalent transgenic insect-resistant cotton plants was done in order to determine the integration, the copy number and the inheritance stability of Bt toxin gene in the transgenic cotton plants. The results indicated that there was a 4.7 kb positive band in the Southern blot when the genomic DNA of the bivalent transgenic insect-resistant cotton plants and the positive control (the plasmid) were digested with HindⅢ respectively. This result proved that the Bt toxin gene had been integrated into the genome of the cotton in full length. There is only one XhoⅠ restriction site in the Bt toxin gene. Southern blot analysis indicated that many copies of Bt toxin gene had been integrated into the genome of the cotton when the genomic DNA of transgenic plants was digested with XhoⅠ. Among them, there were four copies (about 17.7, 8, 5.5 and 4.7 kb in size) existing in all the tested plants of ₃, R₄ and R₅ generations. The preliminary conclusion was that there were more than four copies of Bt toxin gene integrated into the genome of the cotton, among them, more than one copy can express and inherit steadily. This result provides a scientific basis for the breeding of the bivalent insect-resis- tant transgenic cotton plants and its commercialization.     

极谱催化氢波测定白喉类毒素

在0.04mol/LNH3-NH4Cl(pH8.31)支持电解质中,白喉类毒素(DT)产生一个极谱催化氢波,峰电位为-1.89(νs.SCE).该波二阶导数峰电流与DT浓度在1.2～2.0μg/mL内有线性关系,可用于生物样本中DT含量的测定.