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Biomedical subjects

R Schrek

Publications and source records attributed to R Schrek.

At least 37 records · Page 2Linked to original sources
PubMed1976

A colchicine-sensitivity test for leukaemic lymphocytes.

Non-dividing lymphocytes from patients with chronic lymphocytic leukaemia were more sensitive than normal lymphocytes to reagents as prednisolone, cytarabine, vincristine and colchicine. The maximum difference was obtained when the cells were incubated with colchicine at 37 degrees C for 20 h. The sensitivity was measured by a 'sensitivity index' which was an estimate of the average percentage of lymphocytes killed by 1.0 and 0.1 mug/ml of colchicine. The index was 0-15% for lymphocytes from the blood of 14 normal persons and was 61-98% for 23 of 25 leukaemic patients with absolute lymphocyte counts of 8,000 X 10(9)/l or more. 3 of 4 untreated patients with presumptive diagnoses of early leukaemia had low absolute counts of 3,300 to 7,600 X 10(9) lymphocytes/l and high sensitivity indices of 41 to 83%. Tests on treated patients with lymphocytes counts less than 8,000 X 10(9)/l suggested a correlation of the index with remission and relapse. Hairy cells from 3 patients with hairy cell leukaemia were resistant to colchicine. Sensitivity to colchicine seemed useful at a test for leukaemic lymphocytes and as an aid in the haematologic evaluation of patients with chronic lymphocytic leukaemia and malignant lymphoma.

B-Lymphocytes↗
PubMed1976

Inhibition by ionophore A23187 of the cytotoxicity of vincristine, colchicine and X-rays to leukemic lymphocytes.

The ionophore A23187 was tested for its effect on the sensitivity of normal and leukemic lymphocytes to colchicine, vincristine, and X-irradiation. The ionophore was used because it transfers divalent cations through biological membranes and causes the transformation of normal lymphocytes. The sensitivity of the cells was measured by incubation of lymphocyte suspensions with and without reagent at 37 degrees C for one to seven days and counting the number of viable lymphocytes before and after incubation. Viability of the cells was judged by cytologic criteria as visualized by phase contrast microscopy. Lymphocytes were obtained from patients with chronic lymphocytic leukemia and from normal persons. Colchicine and vincristine killed in one day non-dividing leukemic lymphocytes while normal lymphocytes were much less sensitive to the two alkaloids. X-irradiation (1000 rad) killed nearly all leukemic lymphocytes in two days and normal lymphocytes in three days. Ionophore A23187 (2 X 10(-5)M) was moderately toxic to normal but not to leukemic lymphocytes and caused the transformation of both types of cells. The ionophore inhibited the cytocidal action of colchicine and vincristine to leukemic but not to normal lymphocytes and inhibited the action of X-irradiation to both types of lymphocytes. The present findings and a review of the literature suggest the hypothesis that calcium or other divalent ions are involved in the cytotoxicity of colchicine, vincristine, and X-irradiation of leukemic lymphocytes and that there may be an abnormality of the metabolism of divalent ions in leukemic lymphocytes.

Anti-Bacterial Agents↗
PubMed1975

Sensitivity of leukaemic lymphocytes to microtubular reagents.

Tests were make in this and in previous studies on the cytocidal action of cold (27 degrees), heat (43-50 degrees) anoxia, EDTA, colchicine and vincristine on non-dividing lymphocytes from normal individuals and from patients with chronic lymphocytic leukaemia. The reagents were selected for this work because they have been reported to have an effect on microtubules of various types of cells. All of the reagents were found to be more toxic to leukaemic than to normal lymphocytes. These findings are in accord with the hypothesis that vincristine produces a cytocidal effect by its action on the microtubules of leukaemic lymphocytes in interphase, that microtublues of leukaemic lymphocytes are more sensitive to reagents than those of normal lymphocytes, and that microtubules of leukaemic lymphocytes have abnormal cytopharmacological reactions.

Cell Survival↗