Search

Aim: We previously found that low-dose X-ray treatment after systemic administration of acridine orange (AO), which is known to have a low toxicity in animals, inhibited tumor growth in experimental studies using mouse osteosarcoma. In this pilot study, we planned to verify the toxicity of intravenous injection of low-dose AO in humans and investigate the anticancer effect of radiation after systemic AO administration (iAOR) for human cancer., Patients and Methods: Eight patients with terminal cancer were treated with iAOR., Results: None of the patients exhibited an adverse effect from AO injection. Three out of the five patients who received a full course of iAOR exhibited clinical or image-based responses, whereas two patients did not., Conclusion: The systemic administration of AO was confirmed not to be toxic in humans, and iAOR was suggested to be potentially effective against radioresistant cancer., (Copyright© 2018, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

Aim: Development of a non-toxic, fluorescent-based, agar system for the screening of overexpressed bacterial efflux pump systems with common, inexpensive UV accessories., Materials and Methods: Wild type Gram-negative and positive bacteria expressing intrinsic efflux pumps and their progeny that overexpress a specific efflux pump were selected for evaluation of efflux pump activity in a Mueller-Hinton agar, containing increasing concentrations of the non-toxic fluorescent chromophore acridine orange (AO). The method is based on the same principle as the first-generation ethidium bromide method, according to which the concentration of the fluorescent dye that first produces fluorescence of the overlying bacterial colony represents the maximum concentration of the dye that the bacterium can extrude. The higher the concentration needed to produce fluorescence, the greater the ability of the bacterial efflux pump to extrude the dye., Results: Progeny of Escherichia coli, Salmonella enterica serovar Enteritidis and Staphylococcus aureus that over-expressed a given efflux pump fluoresced (i.e. accumulated AO) at concentrations of AO that were much greater than the ones required for the emission of fluorescence by their corresponding wild-type counterpart which expressed an intrinsic efflux pump., Conclusion: The AO agar method readily identifies strains of Gram-negative and Gram-positive bacteria that overexpress efflux pump systems compared to their wild-type progeny.

This study was undertaken to clarify the in vitro effect of acridine orange (AO) on the cell kinetics of mouse osteosarcoma cells, as well as the mechanism of cell growth inhibition induced by AO. A mouse osteosarcoma cell line (MOS), established from a radiation-induced mouse osteosarcoma, was cultured under exposure to 0.05, 0.5, 5, and 50 micrograms/ml of AO, either continuously or for 10 minutes. The cell kinetic analysis was performed using the following parameters: tumor cell growth by trypan blue exclusion test, mitotic activity, DNA synthetic activity by BrdU labeling and DNA ploidy by cytofluorometry. The results showed that continuous exposure to 5 and 50 micrograms/ml of AO or 10 minute exposure to 50 micrograms/ml of AO quickly killed the tumor cells within 12 hours, whereas continuous exposure to 0.5 microgram/ml of AO or 10 minute exposure to 5 micrograms/ml of AO gradually inhibited tumor cell growth. Under the latter conditions, mitotic activity was rapidly and completely inhibited within 48 hours but DNA synthetic activity was not completely inhibited even after 96 hours. DNA ploidy analysis demonstrated that most of the tumor cells arrested at the S-G2 phase after 12 hours, followed by G2 phase arrest after 24 hours and progressive DNA synthesis to a higher DNA ploidy class after 48 to 96 hours. We therefore concluded that a high concentration of AO has a strong cytocidal effect due to cytotoxicity whilst a moderate concentration of AO induces progressive and synchronous polyploidization by mitotic inhibition without DNA damage in MOS cells. We presume that this in vitro effect on MOS cells may be caused by protein synthetic inhibition after transfer RNA inactivation caused by AO binding.

The inhibitory activity of lignin against nitrosoguanidine (MNNG)- and acridine orange (AO)- induced mutagenesis was examined using two microbial systems: green unicellular flagellate Euglena gracilis and Salmonella typhimurium TA100 and TA97. To verify the hypothesis that the above mentioned mutagens may generate some oxidant species and subsequently free radicals, or they may interact with lignin, two physico-chemical measurements were performed. Lignin at a tested concentration (100 micrograms/ml) decreases Euglena-bleaching activity of MNNG by 67.7% and AO by 99.7%. Percentage of MNNG-induced revertants of S. typhimurium was also decreased substantially by lignin. We conclude that our results indicate the possible mechanisms behind the antimutagenic/anticarcinogenic effects of lignin: namely, scavening of reactive oxygen species produced by MNNG and binding of AO itself.