Induction of sister-chromatid exchanges and cell-cycle delays in human lymphocytes by vitamin A alone or in combination with melphalan and caffeine.

In cultured human lymphocytes vitamin A was found to increase SCE rates, to reduce the mitotic index and to have no effect on cell kinetics. Vitamin A induces cytotoxic effects: in combination with melphalan (MELPH), as can be deduced from the resulted synergism on induction of SCEs, the produced cell division delay and the suppressed mitotic index; in combination with caffeine (CAF), producing synergism on induction of SCEs and suppressing the mitotic index; and in combination with MELPH and CAF, producing cell-cycle delays and reducing the mitotic index.

Induction of sister-chromatid exchange in human lymphocytes by vitamin B6.

Vitamin B6, or pyridoxine hydrochloride, enhanced sister-chromatid exchange (SCE) rates in cultured normal human lymphocytes. No increase was found in SCE frequency when lymphocytes were treated with pyridoxal-5-phosphate (P-5-P) or 4-pyridoxic acid (4-PA) to which vitamin B6 is finally converted.