在高浓度1,4-丁二醇中酶促合成去B链C端六肽胰岛素

用含80％1,4-丁二醇的混合溶剂,以胰蛋白酶酶促,由去八肽胰岛素(DOI)合成了去六肽胰岛素(DHI),总产率为35％。1,4-丁二醇的溶解性能好,在浓度高达80—90％时不明显抑制酶活力,DOI的氨基无需保护,溶液中无高聚物或沉淀形成。     

抗人肺癌细胞单克隆抗体的制备及其特性的研究

用人肺鳞癌细胞LTEP-78细胞系免疫Blab/c小鼠获得3株抗人肺癌细胞的单克隆抗体杂交瘤系。其中BLTI-01株经六次克隆化培养,体外传代8个月以上。BLTI-01与白细胞抗原及血型抗原基本上无交叉反应;与骨髓细胞无交叉反应;与癌胚抗原和胎甲球蛋白不相关;与肺鳞癌、肺腺癌细胞系及部分其它肿瘤细胞呈阳性反应。     

Studies on the induction and expression of T cell-mediated immunity. XIV. Antigen-nonspecific oxidation-dependent cellular cytotoxicity (ODCC) mediated by sodium periodate oxidation of cytotoxic T lymphocytes

Alloimmune murine thymus-derived cytotoxic lymphocytes (CTL) generated in vivo or in vitro are shown to lyse antigen-nonspecific target cells (tumor cells, Con A, and LPS blasts) following treatment of CTL with an oxidizing agent, sodium periodate (NaIO4). It has been shown that NaIO4 oxidizes terminal sialic acid residues of cell surface macromolecules. The presence of reactive aldehyde groups, generated by NaIO4 modification, is required for the expression of antigen-nonspecific cytotoxicity because treatment of modified cells with a reducing agent such as potassium borohydride (KBH4) resulted in the abrogation of cytotoxicity. However, KBH4 treatment of unmodified or NaIO4-modified CTL has no effect on antigen-specific cytotoxicity. The modification of CTL by NaIO4 is sufficient to lead to the formation of lymphocyte-target cell conjugates and lysis of bound targets. Monoclonal antibodies directed against the Lyt-2 antigens of CTL, but not Lyt-1 antigens, in the absence of complement inhibited the nonspecific cytotoxicity resulting from NaIO4 modification of effector lymphocytes. These findings suggest that the mere interaction with or perturbation of appropriate cell surface molecule(s) of effector lymphocytes such as Lyt antigens by receptor-ligand interaction in SCMC or by NaIO4 modification in ODCC may lead to the expression of cytotoxicity. The present studies demonstrate a functional role of surface carbohydrates on CTL in cell-to-cell recognition and interactions. Furthermore, the results suggest that target cell modification is not a requisite for recognition and lysis in an antigen-nonspecific cytotoxic system such as ODCC. However, partial blocking of ODCC by alloantibodies directed against the H-2 of unmodified target cells suggests that NaIO4-modified CTL recognize unrelated target H-2 antigens. The implication of these findings on the molecular mechanism of cell-mediated cytotoxicity is discussed.     

Studies on the induction and expression of T-cell-mediated immunity. XIII. Membrane-associated antigens of cytotoxic T lymphocytes involved in cytotoxicity

An xenogeneic rat anti-mouse T-cell serum, designated RAT*, has been shown to block the cytolytic activity of cytotoxic T lymphocytes (CTL) at a postbinding step. RAT* serum or the IgG fraction was extensively absorbed with the target cell, P815, a DBA mastocytoma, and used with or without further absorption to immunoprecipitate specific molecules from radiolabeled membrane extracts of CTL derived from either in vivo-allosensitized mice or from cytotoxic clones maintained in in vitro cultures. Cell surface sialic acid residues were labeled by oxidation with sodium periodate (NaIO4) and reduction with tritiated sodium borohydride ([3H]NaBH4). Alternatively, cell surface proteins were labeled with 125I by lactoperoxidase-catalyzed iodination. Nonidet P-40 (NP-40)-solubilized radiolabeled membranes were then immunoprecipitated with RAT* serum and analyzed by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis (PAGE). Three membrane-associated molecules of 95,000, 140,000 and 180,000 Mr were found by such analysis. The sensitivity of these three molecules to trypsinization and their susceptibility to labeling with [3H]NaBH4 suggested that they are glycoproteins. Moreover, when RAT* serum or the IgG fraction was absorbed with various cell types, its ability to immunoprecipitate the three molecules correlated with its ability to block cytolysis. Adsorption of RAT* serum with CTL, but not with nonimmune thymocytes, significantly reduced the ability of RAT* serum to inhibit cytotoxicity and to immunoprecipitate the 95k, 140k, and 180k molecules. Thus, these findings suggest that one or more of these cell surface molecules of CTL may be involved in the cytolytic process.     

Nucleoside Diphosphate-sugar 4-Epimerases I. Uridine Diphosphate Glucose 4-Epimerase of Wheat Germ

Uridine diphosphate (UDP)-glucose 4-epimerase (EC 5.1.3.2) has been purified over 1000-fold from extracts of wheat germ by MnCl₂ treatment, (NH₄)₂SO₄ fractionation, Sephadex column chromatography, and adsorption onto and elution from calcium phosphate gel. The enzyme has a pH optimum of 9.0. Km values are 0.1 mm for UDP-d-galactose and 0.2 mm for UDP-d-glucose. NAD is required for activity; K_a = 0.04 mm. NADH is an inhibitor strictly competitive with NAD; K_i = 2 μm. Wheat germ also contains UDP-l-arabinose 4-epimerase (EC 5.1.3.5) and thymidine diphosphate (TDP)-glucose 4-epimerase which are distinct from UDP-glucose 4-epimerase.     

胎盘型碱性磷酸酶的纯化及部分性质的研究

 <正> 胎盘型碱性磷酸酶(P-ALP)是碱性磷酸酶(EC3.1.3.1.ALP)的一种同工酶。P-ALP除出现于妊娠妇女血清外,一些学者还从恶性肿瘤患者血清中发现此酶,并证明它是一种特异性较强的肿瘤标志物。据此,建立P-ALP的简易纯化方法,制备纯度较高的酶制品是建立P-ALP灵敏的微量检测法的先决条件。本文报道以L-苯丙氨酸(L-phe)为配基,用氯代环氧丙烷活化Sepharose 4B的亲和层析法,从人胎盘纯化P-ALP,并对其部分性质进行了研究。     

胡萝卜人工种子在无菌条件下的贮藏及贮藏中种子活力变化

对用海藻酸钙包埋胡萝卜体细胞胚(0.6—2mm)制作的人工种子进行贮藏研究,发现低温及干燥均能在一定程度上抑制人工种子萌发。失水率达67%的种子,2℃贮藏60天后, 在发芽培养基上发芽率为100%,7天内的成苗率达80%。未经贮藏的对照种子发芽率为100%,成苗率为76%。无论在“种皮”还是在胚胎悬浮培养液中加入脱落酸或香豆素,都能抑制胚的生长,但也促进了胚的衰老。铝箔袋内密闭贮藏期间种子不萌发,但活力下降快。随着贮藏时间的延长,种子的活力指数、脱氢酶活性、氧吸收率都呈下降趋势。     

Microscopic visualization of insect cell-bubble interactions. I: Rising bubbles, air-medium interface, and the foam layer.

Through the use of microscopic, high-speed video technology, the interactions of two suspended insect cell lines, Trichoplusia ni (TN-368) and Spodoptera frugiperda (SF-9), with air and oxygen bubbles were studied. Events such as cell-bubble attachment, cell-bubble collision, cell transport into the foam layer, and trapping of cells in the foam layer are presented and discussed. Based on these observations and those in a companion paper (Chalmers, J. J.; Bavarian, F. Biotechnol. Prog. 1991, following paper in this issue) and the experimental and theoretical work of other researchers, several mechanisms of cell damage as a result of sparging are presented.     

The pig as an intermediate host for Taiwan Taenia infection

Eggs (1000-100,000/animal) of Taiwan Taenia were inoculated per os into 14 Small-Ear-Miniature (SEM), 19 Landrace-Small-Ear-Miniature (L-SEM), and 5 Duroc-Yorkshire-Landrace (DYL) pigs. These animals were sacrificed 7-107 days after infection. Thirty-four pigs were found to be infected with Taiwan Taenia cysticerci and the infection rates of SEM, L-SEM, and DYL were 86%, 89% and 100% respectively. The cysticerci recovery rates of SEM, L-SEM and DYL pigs were 27.2%, 1.7% and 0.27% respectively. Cysticerci were recovered only from the livers and none were found in muscles, viscera or other parts of the carcasses. More cysticerci were located in the liver parenchyma (71%) than on the liver surface (29%). Taiwan Taenia cysticerci were smaller than those of classical T. saginata or T. solium. Moreover, Taiwan Taenia cysticerci had 2 rows of rudimentary hooklets on the scolex. The results of this study indicate that young pigs are good intermediate hosts for Taiwan Taenia and that the SEM pig is a satisfactory host for experimental studies with this tapeworm. These results were similar to other studies with different geographic strains of the T. saginata-like tapeworm in the Far East. These strains appear to be the same and possibly a new species.