Advances in the design of special cryosurgical apparatus in China

Advances in the design of special cryobiomedical apparatus and a review of the trend of developments in the field of cryosurgery in China are discussed. The typical structure of two special cryoprobes for treatment deep in the body and the technology of designing these probes are presented in detail. Some cases which are treated successfully with the above cryoprobes will also be discussed. The experimental aspects of heat transfer in frozen tissue and of the temperature profiles both of a human brain during surgery and of the cryoprobe are described. Other improvements in the field of cryosurgical devices, e.g., four main ways of attaching freezing tips to cryoprobes during surgery and an LN2 transfer tube with high dexterity are also presented. Finally, the development of commercial cryosurgical apparatus in China is also discussed.     

Subunit structure of the dihydrolipoyl transacylase component of branched-chain alpha-keto acid dehydrogenase complex from bovine liver. Mapping of the lipoyl-bearing domain by limited proteolysis

To characterize the lipoyl-bearing domain of the dihydrolipoyl transacylase (E2) component, purified branched-chain alpha-keto acid dehydrogenase complex from bovine liver was reductively acylated with [U-14C] alpha-ketoisovalerate in the presence of thiamin pyrophosphate and N-ethylmaleimide. Digestion of the modified complex with increasing concentrations of trypsin sequentially cleaved the E2 polypeptide chain (Mr = 52,000) into five radiolabeled lipoyl-containing fragments in the order of L1 (Mr = 28,000), L2 (Mr = 24,500), L3 (Mr = 21,000), L4 (Mr = 15,000) to L5 (Mr = 14,000) as determined by the autoradiography of sodium dodecyl sulfate-polyacrylamide gel. In addition, a lipoate-free inner E2 core consisting of fragment A (Mr = 26,000) and fragment B (Mr = 22,000) was produced. Fragment A contains the active site for transacylation reaction and fragment B is the subunit-binding domain. Fragment L5 and fragment B were stable and resistant to further tryptic digestion. Mouse antiserum against E2 reacted only with fragments L1, L2, and L3, and did not bind fragments L4, L5, A, and B as judged by immunoblotting analysis. The anti-E2 serum strongly inhibited the overall reaction catalyzed by the complex, but was without effect on the transacylation activity of E2. Measurement of incorporation of [1-14C]isobutyryl groups into the E2 subunit indicated the presence of 1 lipoyl residue/E2 chain. Based on the above data, a model is proposed in which the lipoyl-bearing domain is connected to the inner E2 core via a trypsin-sensitive hinge. The lipoyl-bearing domain contains five consecutive tryptic sites (L1 to L5), with the L1 site in the hinge region, and the L5 site next to the terminal lipoyl-binding sequence. An exposed and antigenic region is located between L1 and L4 tryptic sites of the lipoyl-bearing domain. The region accounts for about 24% of the E2 chain length. Binding of antibodies to this region probably impairs the mobility of the lipoyl-containing polypeptide, resulting in an interruption of the active-site interactions that are necessary for the overall reaction. The lack of antigenicity and resistance to tryptic digestion indicate a highly folded conformation for fragment L5, the limit polypeptide carrying the single lipoyl residue.     

单纯疱疹病毒Ⅱ型DNA克隆片段的限制酶切分析

本文采用10种限制性内切核酸酶分析了单纯疱疹病毒Ⅱ型(HSV-2)335株DNA BglⅡ8种克隆片段共12个重组质粒。发现了HSV-2 DNA L链末端区域有限制酶切位点的变异并对HSV-2 DNA单一序列区域和末端重复区域的稳定性进行了初步讨论。本文应用末端标记技术和末端杂交分析法对编码糖蛋白D的HSV-2 DNA BglⅡL片段和含有形态学转化基因的HSV-2DNA BglⅡN片段进行了详细的限制性内切核酸酶物理图谱分析。     

光合能量代谢对C_3植物光呼吸的调节作用

C_3植物光呼吸与光合作用关系受光合能量代谢状况的调节。在外界无CO_2和照光条件下,贮藏性光合产物经某种转化途径能“回迁”光合与光呼吸碳循环并显著地受到光合能量代谢的影响。在无CO_2或低CO_2浓度、高光强条件下,此碳素“回迁”过程对协调光合能量代谢与光合碳素代谢平衡,可能起重要作用。     

用三维图象量测卵裂前蛙卵膜分子的三维运动

两栖类卵第一次卵裂前,缩时电影显示出卵表面有收缩波。由于卵的体积未变,在收缩时卵的高度必然增加。Sawai(1978)利用棱镜侧面摄取了蝾螈卵轮廓的高度变化,证实了卵裂前卵最高处的高度确有增加。但这一方法不能测知整个卵表面各处的高度变化,而且仅是二维的。在林蛙卵上,我们用荧光漂白恢复技术发现第一次卵裂前卵表面分子有规律性的流动,推测这是卵球的张弛。为了进一步     

绿茶抗氧化剂成分抑制突变作用的初步研究

绿茶水溶性提取物及茶叶中抗氧化剂成份具有明显的抑制AFB_1及Bap诱导的鼠伤寒沙门氏菌回复突变作用。这种抗氧化剂成份还可以抑制AFB_1和Bap诱导的V79细胞基因正向突变,以及AFB_1诱导的V79细胞SCE和染色体畸变。本实验结果提示,绿茶中抗氧化剂成份可能对AFB_1及Bap的致癌性具有抑制作用。本文就茶叶抗氧化剂抑制突变的可能机制进行了初步讨论。     

Analysis of tissue-specific methylation patterns of mouse mammary tumor virus DNA by two-dimensional Southern blotting.

We used a two-dimensional Southern blotting procedure to analyze the tissue-specific methylation patterns of the five endogenous mouse mammary tumor viruses in the GR/A mouse strain. Our findings suggest that in certain tissues (brain, kidney, and liver) all proviruses are extensively methylated. In other tissues (spleen, placenta, and testes) all proviruses are hypomethylated to some degree. In these tissues individual proviruses display both quantitative and qualitative differences in methylation. We interpret the general patterns of tissue-specific hypomethylation in terms of a "hitch-hiker" model: mouse mammary tumor virus proviral methylation patterns reflect the tissue-specific activity of neighboring sequences. The observation that certain sites on particular proviruses are differentially methylated in a tissue-specific fashion may reflect tissue-specific differences in the makeup or conformation, or both, of proviral-containing chromatin.     

辣椒四个品种的核型研究

本文对我国栽培辣椒Capsicum annuum L.的四个品种即汉川椒、华椒一号、牛角椒和二金条进行了核型分析,其染色体数目均为2n=2x=24,核型公式均为2n=24=20m+2sm+2st,但汉川椒和华椒一号具一对随体,牛角椒和二金条具两对随体。本文还对它们的进化关系进行了讨论。     

辣椒四个品种的核型研究

本文对我国栽培辣椒Capsicum annuum L.的四个品种即汉川椒、华椒一号、牛角椒和二金条进行了核型分析,其染色体数目均为2n=2x=24,核型公式均为2n=24=20m+2sm+2st,但汉川椒和华椒一号具一对随体,牛角椒和二金条具两对随体。本文还对它们的进化关系进行了讨论。