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Biomedical subjects

Y Keisari

Publications and source records attributed to Y Keisari.

63 records · Page 4Linked to original sources
PubMed1980

A simple colorimetric method for the measurement of hydrogen peroxide produced by cells in culture.

A simple, rapid and inexpensive method for the measurement of hydrogen peroxide (H2O2) produced by cells in culture is described. The assay is based on the horseradish peroxidase (HRPO)-mediated oxidation of phenol red by H2O2 which results in the formation of a compound demonstrating increased absorbance at 610 nm. A linear relationship between absorbance at 610 nm and concentration of H2O2 was found in the 1--60 microM (1--60 nmoles/ml) range. Due to the non-toxic character of phenol red and HRPO, the assay permits measurement of H2O2 production and release by macrophages for time intervals of 5--60 min under regular tissue culture conditions. Using this assay, the ability of a number of agents to induce H2O2 release by guinea pig peritoneal macrophages was demonstrated. These agents were: phorbol myristate acetate (PMA), opsonized zymosan, concanavalin A (Con A), wheat germ agglutinin (WGA), N-formyl-methionyl-leucyl-phenylalanine (FMLP) and A23187.

Animals↗
PubMed1978

Degradation of cell-bound antibodies by tumor cells from C57BL/6 mice.

A kinetic study of the disappearance of sensitizing antibody from metabolizing EL 4 cells in C57BL/6 mice revealed that this disappearance was at least partly due to the degradation of the antibody into dialyzable products. The degradation took place at 37 degrees C, but not at 4 degrees C, and occurred on or inside the cell. The process was specific inasmuch as only those IgG molecules that could bind to the cells were degraded, whereas unrelated third-party antibodies present in the culture medium remained intact. Although nonmalignant cells also have the capacity to degrade cell-bound antibodies, possibly the degradation of proteinaceous structures on antitumor effector mechanisms is, in part, responsible for decreased antitumor immunity.

Animals↗
PubMed1975

The specific blocking of humoral immune cytolysis mediated by anti-tumor antibodies degraded by lysosomal enzymes of tumor origin.

The IgG fraction from rabbit antisera against a mouse plasmacytoma (RaPCT-IgG) was incubated, under acidic conditions, with lysosomal extracts (LE) derived from the corresponding tumors. The LE-treated IgG demonstrated a significant decrease in its complement-dependent cytotoxic potential when compared to RaPCT-IgG incubated without LE under the same conditions (control IgG). Ammonium sulfate (AS) precipitation of the control IgG and the LE-treated IgG preparations at 40% saturation of AS revealed that some of the IgG lost its precipitability at this AS concentration after LE treatment, but could be precipitated at 60% or 70% saturation. The LE-treated IgG and control IgG fractions that precipitated by 40% saturated AS showed similar gel filtration profiles. The LE-treated IgG fraction precipitating at 70% saturation of AS (but not at 40%) showed a different gel filtration profile. This fraction was separated into several subfractions, some with an apparent lower molecular weight. Some of these subfractions which still contained antigenic IgG lacked any expression of antigenic Fc, and were not cytotoxic to tumor cells. They could, however, rebind to tumor cells and block the complement-dependent cytotoxic activity of native RaPCT-IgG. Lysosomal enzymes of tumor origin seem, therefore, to convert cytotoxic anti-tumor antibodies into molecules devoid of Fc but still retaining their antigen binding activity. Such an activity, if occurring in vivo might enhance tumor growth.

Ammonium Sulfate↗
PubMedDate not supplied

Thymic humoral factor-gamma 2 augments immune cell response and exerts antitumor activity in murine model systems.

The immunomodulatory and antimetastatic/antitumor activity of thymic humoral factor-gamma 2 (THF-gamma 2) was evaluated in BALB/c-mice. Daily subcutaneous applications (7 consecutive days, 20, 200 ng of THF-gamma 2 per injection/mouse) upregulated counts of thymocytes and peripheral blood cells in tumor bearing mice. To check the influence of THF-gamma 2 treatment on the growth of experimental metastases, RAW 117 H10 lymphosarcoma cells or L-1 sarcoma cells were intravenously inoculated into BALB/c-mice to establish liver or lung metastases, respectively. Local tumor growth was induced by subcutaneous injection of L-1 sarcoma cells. THF-gamma 2 was subcutaneously administered daily for 7 consecutive days starting 24 hrs after tumor cell challenge. Organ colonization as well as local tumor growth were investigated on day 14 after tumor cell inoculation and demonstrated a statistically significant (p < 0.05) reduction of experimental liver and lung metastases and local tumor growth for THF-gamma 2 treated mice.

Adjuvants, Immunologic↗