Increased radiation toxicity by enhanced apoptotic clearance of HL-60 cells in the presence of the pentapeptide thymopentin, which selectively binds to apoptotic cells.

Radiotoxic insult to cells is associated with genetic instability and heritable damage [Mutat. Res. 517 (2002) 173]. A strengthened response to such insult by enhanced apoptotic clearance, which would be associated with anti-inflammatory [Nature 390 (1997) 350; Nature 407 (2000) 784] and anti-necrotic intercellular signaling [Nature 418 (2002) 191], has been previously reported. The pentapeptide thymopentin (TP5) improves immunological parameters in cancer patients following radiotherapy without clinically observable side effects. We assessed the effects of TP5 on human promyeloid leukemia HL-60 cells exposed to therapeutic (2Gy) doses of X-rays. We observed an increased accumulation of cells in the G2/M phase of the cell cycle after irradiation when treated with TP5. However, TP5 had no effect on the cell cycle distribution of non-irradiated HL-60 cells. Additionally, TP5 treatment of irradiated cells increased the number of cells undergoing apoptosis. Furthermore, TP5 was found to selectively bind to apoptotic cells. These findings represent a promising and novel approach employing TP5-mediated modulation of cellular radiation response to augment both clinical gain in radiation oncology and safety measures for radiation protection.

Antimicrobial activity of dequalinium chloride against leading germs of vaginal infections.

Dequalinium chloride (CAS 522-51-0) and povidone iodine (CAS 25655-41-8) are known as antiseptic agents and used in the local treatment of vaginal infections. Clotrimazole (CAS 23593-75-1) is an anti-fungal drug and applied primarily in the therapy of vulvo-vaginal candidiasis and to a lesser extent in bacterial vaginosis and trichomoniasis. However, antimicrobial activities of those three agents in comparison to each other have not been reported so far. To address this issue the antimicrobial activities of these agents against 18 germs relevant to vaginal infections were determined. The tested species are representatives of the genera Staphylococcus, Streptococcus, Enterococcus, Listeria, Escherichia, Proteus, Gardnerella, Bacteroides, Prevotella, Porphyromonas, Candida, and Trichomonas. All micro-organisms were susceptible to dequalinium chloride with the exception of Proteus mirabilis. At a given dose, the activity of dequalinium chloride was higher as compared to the other substances. In view of its wide antimicrobial spectrum dequalinium chloride is an efficient alternative in the local therapy of vaginal infections such as fluor vaginalis, bacterial vaginosis, aerobic vaginitis, vulvo-vaginal candidiasis and trichomoniasis.