Biomedical subjects
Publications and source records attributed to G L Irvin.
Tritiated thymidine was found to affect the cell cycle progression of phytohemagglutinin-stimulated human lymphocytes. By means of flow cytometry a statistically significant increase in the G2 and M phases of the cell cycle was observed in cultures with low concentrations of tritiated thymidine added 18 hours before the cultures were harvested.
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A calf thymocyte crude aqueous extract was tested for DNA synthesis inhibitory activity using phytohemagglutinin-stimulated human peripheral blood lymphocytes. Inhibition of DNA synthesis was assayed using tritiated thymidine and flow cytometry. Although the calf thymocyte crude extract inhibited tritiated thymidine incorporation by over 50%, only very slight changes in the flow cytometric analysis were observed. When dibutyryl-cyclic adenosine monophosphate was used as an inhibitor, a correlation in terms of the inhibition of tritiated thymidine to the inhibition by flow cytometry was observed.
A nonparametric statistical test for the analysis of flow cytometry derived histograms is presented. The method involves smoothing and translocation of data, area normalization, channel by channel determination of the mean and S.D., and use of Bayes' theorem for unknown histogram classification. With this statistical method, different sets of histograms from numerous biological systems can be compared.
By treating nonsensitized C57BL/6J spleen derived lymphocytes with EL-4 tumor cell directed xenogeneic extracted RNA we were able to monitor early changes in cellular DNA content by flow cytometric (FCM) analysis and 3H-thymidine uptake. These kinetic parameters were correlated with cell mediated cytotoxicity which appeared as early as 8 hr after activation as measured by release of chromium-51 from labeled EL-4 target cells. Flow cytometric analysis and 3H-thymidine uptake data shown peak S phase activity at 72 hr. Maximum cytotoxicity was observed at 48 hr. Cell cycle kinetic parameters were correlated with the appearance of cell mediated cytotoxicity.
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A prospective study designed to emphasize and quantitate the operative risk of patients preparing to undergo surgery for the treatment of complicated peptic ulcer disease is presented. Data were gathered from 347 consecutive patients operated on with benign gastric and/or duodenal ulcers in a Veterans Hospital over an 8-year period. Resident surgeons performed all operations and for the most part decided on the operative procedure used, with advice from attending faculty. Preoperative factors influencing the operative mortality in 34 patients were compared with those in surviving patients and subjected to a multivariant discriminant function analysis by computer. Ten variables were identified as being significantly different (P less than 0.05-P less than 0.01) between the survivor and non-survivor groups. Using the discriminant weights of these variables, a computer program was written to calculate the 30-day operative mortality of any preoperative patient based on this past experience. The accuracy of the program is excellent in good risk patients; i.e., a predicted greater than 90% chance of survival was correct 98.9% of the time with 3 deaths in 279 patients. Patients at the low end of the scale (less than 10%) were predicted with 85% accuracy. In the last 8 months, 29 patients have undergone surgery after prospective computer assessment of their operativ risk. All have survived with a predicted chance of greater than 50%. Four patients died with survival chances predicted at 4, 2, 1, and 1%. The computer may be used as an educational vehicle for sharpening our preoperative assessment of a patient with ulcer disease, particularly regarding operative risk.
Tumor-specific immunoprophylaxis was achieved in C57BL/6J mice against EL 4 leukosis cell challenge by sensitization of the syngeneic host with multiple ip injections of irradiated EL 4 cells. A minimal radiation dose was used to replication-block EL 4 cells before inoculation, as defined by dose-response analysis of irradiated EL 4 cells. Multiple ip injections of irradiated EL 4 cells stimulated development of significant, yet relatively low, levels of cytotoxic lymphoid activity (CLA) in lymphoid cells of the peritoneal exudate as measured by in vitro 51Cr-release cytotoxicity assays. The specific temporal and frequency dependencies of the inoculation regimen for achieving immunoprophylaxis indicated that, in addition to CLA, other, short-lived, immune processes were important in the tumor rejection. These observations showed the capacity of the C57BL/6J host for tumor-specific immune recognition and rejection of the syngeneic EL 4 leukemia. The tumor rejection could be elicited solely by inoculations of irradiated EL 4 cells and did not require exogenous amplifiers, such as immunoadjuvants, chemical modifiers, and/or allogeneic immune information transfer.