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G L Shen

Publications and source records attributed to G L Shen.

11 recordsLinked to original sources
PubMed1990

[Studies on sensor for L-ascorbic acid using biotissue slice].

Bioselective membrane electrode for L-ascorbic acid has been made with tissue slices. It is made from porcine liver tissue slice covering an oxygen electrode. The influence of buffer mediator, pH, temperature, antiseptics, slice thickness, etc. on the response characteristics of the electrode was examined. In the presence of copper ions, a linear relationship between dynamic response of the electrode and the logarithm of concentration of L-ascorbic acid was observed for the range of 21.14 micrograms/ml to 352.3 micrograms/ml, with a correlation coefficient of 0.9996 and the Michaelis constant of 0.8 mmol/L. The electrode has been used to determine L-ascorbic acid in drugs, the analytical results were satisfactory.

Animals↗
PubMed1989

The epitope specificity and tissue reactivity of four murine monoclonal anti-CD22 antibodies.

The CD22 antigen is expressed on the surface of normal human B cells and some neoplastic B cell lines and tumors. Previous cross-blocking studies using a panel of monoclonal anti-CD22 antibodies have defined four epitope groups, termed A-D. In the present studies, we have further dissected the epitopes recognized by four monoclonal anti-CD22 antibodies using immunoprecipitation and cross-blocking techniques, immunofluorescence analyses with a variety of cell lines, and immunoperoxidase analyses of 36 normal human tissues. Two of the antibodies, HD6 and RFB4, have been described previously, and two, UV22-1 and UV22-2, are described in this report. Our studies indicate that the four monoclonal antibodies show unexpected complexities in their reactivity with CD22+ and CD22- cells and their reactivity with solubilized CD22 molecules. The four antibodies, which recognize epitopes defined previously as CD22-A and CD22-B, further subdivide these epitope clusters into four determinants, A1, A2, B1, and B2. Furthermore, only two of the antibodies, RFB4 and UV22-2, are B cell-specific. In summary, our data indicate that RFB4 and UV22-2 would be the antibodies of choice for constructing immunotoxins to treat B cell tumors.

Animals↗
PubMed1989

[Thermotolerant kinetics of HEp-2 cells and effect of thermotolerance on cytotoxicity of nitrocaphane].

The thermotolerant kinetics of HEp-2 cells and its effect on cytotoxicity of Nitrocaphane (NC) were studied by colony formation assay. HEp-2 cells were exposed to two equal thermal doses (44 degrees C, 30 min) spaced at 0-24 hr intervals during which the cells were incubated at 37 degrees C. The maximum thermotolerance developed at the 8th hr and then gradually declined. Thermal dose survival curve even up to 2.5 hr of continuous exposure to 44 degrees C, no development of thermotolerance was demonstrated. If the cells were preheated at 44 degrees C for 30 min, and returned to 37 degrees C for 10 hr and then received the second heating at 44 degrees C for 3 hr, the slope of survival curve decreased (D0 = 2.26 hr). Thermotolerant ratio was 5.9. Thermosensitive HEp-2 cells were turned into thermotolerant cells by preheating at 44 degrees C, 30 min and returning to 37 degrees C for 10 hr. The thermotolerant cells showed resistance to drug or heat when they were exposed to NC or NC combined with heat.

Antineoplastic Agents↗
PubMed1988

Evaluation of four CD22 antibodies as ricin A chain-containing immunotoxins for the in vivo therapy of human B-cell leukemias and lymphomas.

Ricin A chain-containing immunotoxins (IT-As) specific for the human B-cell antigen, CD22, were prepared from 4 monoclonal antibodies (MAbs) or their Fab' fragments: RFB4, HD6, UV22-I and UV22-2. The ITs were tested for their ability to kill cells from the Burkitt lymphoma line, Daudi, the pre-B-cell leukemia line, NALM-6, and the myeloma cell line, ARH-77. Daudi expresses high levels of CD22, whereas NALM-6 and ARH-77 express low levels of CD22. The IgG-RFB4-A was highly toxic to all 3 cell lines; it killed 50% of the Daudi cells at a concentration of 1.2 x 10(-12) M and 50% of NALM-6 and ARH-77 cells at concentrations of 1.5 to 2.1 x 10(-11) M. IgG-RFB4-A was 10-30 times more toxic to Daudi cells than were the IgG-As constructed from the other 3 CD22 MAbs and 10 times more toxic than ricin itself. IT-As constructed from the Fab' fragments of the 4 CD22 antibodies were 2 to 5 times less toxic to Daudi cells than their IgG-A counterparts. Fab'-RFB4-A was twice as toxic to Daudi cells as ricin, whereas the other Fab'-As were about 7 times less toxic than ricin. Scatchard analyses of the binding of the radio-iodinated antibodies to Daudi cells showed that the intact RFB4 antibody bound 3-10 times more strongly than the other antibodies, whereas the Fab'-RFB4 bound 1.2 to 3.5 times more strongly than the Fab' fragments prepared from the other antibodies. Thus, the potent cytotoxic activity of the RFB4-As appears to derive, in part, from their superior binding affinity. Prior studies have shown that UV22-I and HD6 cross-react with certain normal human tissues lacking cells of B-cell lineage, whereas UV22-2 and RFB4 are B-cell-specific. This fact, together with its superior potency as an IT-A, suggests that RFB4 is the antibody of choice for preparing Fab'-As or IgG-As for in vivo therapy of human B-cell leukemias and lymphomas.

Animals↗
PubMed1986

Relationship between three different B cell types and the specific efficiency of hybridoma formation.

The kinetic changes of the number of antigen-specific B cell (ASC, sIg+, Ig-non-secreting), preplasma cell (sIg+, Ig-secreting) and plasma cell (sIg-, Ig-secreting) in the spleens of inbred sibling Balb/c mice during the continuous OA immunization process were assayed, and their relationship to the corresponding specific efficiency of the hybridoma formed was compared. The results show: the specific efficiency of hybridoma formation is parallel with the kinetic changes of the number of ASC, but not with the number of preplasma or plasma cells. So we suggest that the antigen activated B lymphocytes in proliferating state, but neither the antibody-secreting cells (i.e. preplasma cell and plasma cell) nor small B lymphocytes are partners fused with the myeloma cells to yield functional hybridoma cells.

Animals↗
PubMedDate not supplied

Enhancement of nitrocaphane cytotoxicity by hyperthermia in vitro.

HEp-2 cells were treated with hyperthermia (39-44 degrees C) and nitrocaphane (NC) at various time intervals. A 1 h exposure to 39 degrees C and 41 degrees C was non-lethal to cells, but it did potentiate the cell killing of NC (1.0 micrograms/ml). It was further shown that the sequence between heat and the drug can affect cell survival. Cell killing effect was decreased when heat was given before or after administration of drug. In contrast the simultaneous administration of these two modalities was synergistic. Maximal thermotolerance of HEp-2 cells was developed using an 8-h interval at 37 degrees C between the cell exposures to two equal thermal doses (44 degrees C, 30 min). HEp-2 cells became thermotolerant when preheated for 30 min at 44 degrees C followed by a 10-h interval at 37 degrees C. The thermotolerant cells showed resistance to subsequent heat at 44 degrees C (D0 = 2.26 h, control D0 = 0.38 h), to subsequent NC treatment, and to heat combined with NC. However, in the thermotolerant cells, cytotoxicity of NC was still enhanced by hyperthermia.

Antineoplastic Agents↗