[Selection of methods for HIV screening of donors' sera and blood products]

Blood and blood products are very important agents of HIV transmission. In this paper, 11,251 samples from 10,422 donors' sera and 150 blood products were screened for anti-HIV by ELISA, PA, IF and WB. The results were all negative. The donors lived in the 10 municipalities and counties of Sichuan Province. We also performed a prospective investigation to learn if these four methods were suitable to different blood products. We found that positive or weak positive reactions of ten occurred when gamma-globulins were detected by IF and ELISA, but the results were negative when gamma-globulins were tested by PA and WB. As a screening assay for anti-HIV, PA is most suitable for gamma-globulin. WB assay is the optimal method for anti-HIV testing in terms of both specificity and sensitivity. However, because the necessary reagents are very expensive and the procedure is time-consuming, we suggest that the WB assay may be used as a confirmatory test for anti-HIV assay in countries and regions where its general use is cost-prohibitive.

[Internalization of monoclonal antibodies against human hepatoma in the target cells]

The monoclonal antibodies against human hepatoma, HAb23, HAb18 and HAb8, were linked with 5 nm colloid gold. They were used to incubate with the target cells, QGY-7703 and SMMC-7721 human hepatoma cell lines, at 4 degree C for 1 hour. The incubated hepatoma cells were divided into 6 groups and then were put into 37 degree C water incubator for 0, 5, 10, 30, 60 and 120 minutes respectively. After washing, the target cells were fixed with Karnovsky's fixative and embedded in Epon 812. There were four intracellular routings for HAb 23, HAb18 and HAb8 to enter the QGY-7703 and SMMC-7721 hepatoma cells: (1) Coated pits coated: The colloid gold-antibodies which clustered in the specialised regions of the surface membrane were invaginated rapidly into the cells to form coated vesicles. (2) Enclosed invagination: One or two colloid gold-antibodies which were attached on the surface membrane were invaginated into the cell by endocytosis. (3) Microvilli involved routing: The microvilli which were adsorbed by the colloid gold-antibodies were broken and then were phagocytized by the cells. (4) Routing via glycocalyx-like material: The glycocalyx-like material which was clustered by the colloid gold-antibodies was invaginated during endocytosis.

[The in vitro induction of antibody responses of human lymphocytes and its application to hybridoma production]

Sources of immunized lymphocytes constitute one of the main obstacles in the production of human monoclonal antibodies. We tried to get them through in vitro immunization. Cells from excised tonsils or trauma spleens were used for the induction of antibody responses in vitro. Antibodies to different antigens including sheep red blood cells, ovalbumin, tetanus toxoid, and hepatitis B surface antigens were induced in 7-14 days' cultures. Taking tetanus toxoid as antigen, we analysed the various factors required for antibody induction with statistics analysis, which included cell separation method, T cell conditioned medium, antigen dosage, serum content, and concentration of mitogen PWM and LPS. The results showed: (1) The cell separation method influenced the antibody production significantly in comparison with other factors. It signified that immune cells' combination was the most influential factor. (2) Serum also constituted quite important influencing factor especially in the later period of culture. However, it did not make much differences if it attended 10% or so. The antigens and mitogens tended to be used at low concentration. (3) Due to the significant variation among individuals and among different antigens, it is suggested to set up the culture system with some flexibility so as to adapt to the variation in cells and antigens from different sources. The present culture system we use includes nylon wall column separation of cells, suitable range of antigens (three doses instead of one), and either 10% T cell conditioned medium or a mixture of 1 microgram PWM/ ml + 0.1 microgram LPS/ml. The human B lymphocytes stimulated in vitro with tetanus toxoid were used for the construction of human hybridomas.

[Effect of liuwei dihuang decoction and its compatible prescriptions on lipid peroxide and lipofuscin]

Our experiment has shown that liuwei dihuang Decoction can decrease the contents of lipid peroxide in the serum as well as lipofuscin in the liver of the older mice to the level of the younger ones, while the two compatible prescriptions derived from the decoction, "Three invigorators" and "Three purges", cannot produce the same effect. All the three forms of prescription have no action on the lipofuscin in the heart.

Dynamics of the distribution of cyclic AMP-dependent protein kinase in living cells

The intracellular distribution of regulatory molecules may provide a mechanism for controlling gene expression. The subcellular location of cAMP-dependent protein kinase was analyzed in living cells by microinjection of regulatory and catalytic subunits labeled with fluorescein. Following microinjection, type I holoenzyme was found in the cytoplasm and remained there for up to 4 hr. Upon dissociation of holoenzyme with 8-bromo-cAMP, free catalytic subunit appeared in the nucleus while regulatory subunit remained in the cytoplasm. Similarly, purified catalytic subunit was transported to the nucleus in the absence of elevated intracellular cAMP following its introduction into the cytoplasm. Translocation to the nucleus was apparent within 10 min and persisted for at least 2 hr. In contrast, purified regulatory subunit, like holoenzyme, was maintained in the cytoplasm. These results suggest that one function of the type I regulatory subunit is to serve as a cytoplasmic anchor, sequestering the catalytic subunit in the cytoplasm until holoenzyme dissociates in response to increased cAMP.