Cytogenetic and antineoplastic effects by newly synthesised steroidal alkylators in lymphocytic leukaemia P388 cells in vivo

Genotoxicity induced in vitro by water-soluble indoor PM2.5 fractions in relation to heavy metal concentrations

The aim of the present study was to examine the genotoxicity induced by water-soluble fractions of particulate matter (PM) and its potential relation with heavy metals. For this purpose, the genotoxicity induced on human peripheral lymphocytes by water-soluble PM_2.5 (particles with aerodynamic diameter ≤ 2.5 μm) collected from the indoor air of various workplaces in Greece (n = 20), was examined by the Sister Chromatid Exchange (SCE) induction assay and assessed in relation to the concentrations of the heavy metals Cu, Pb, Mn, Ni, Co, Zn, Cr, and Cd. The number of SCEs per metaphase (SCEs/metaphase), as an indicator of genotoxicity, the proliferation rate index (PRI), as an indicator of cytostaticity, and the mitotic index (MI), as an indicator of cytotoxicity, were measured and assessed in three water-soluble fractions of PM_2.5: the total water-soluble fraction WS_A (filtered through 0.45 μm), the dissolved fraction WS_B (filtered through 0.22 μm), and the non-chelexed dissolved fraction WS_C (filtered through Chelex-100 resin). Results showed statistically significant number of SCEs/metaphase in all water-soluble PM_2.5 fractions in relation to the control with large variabilities across the workplaces as a result of variations in indoor conditions, sources, and/or activities. The concentrations of genotoxicity were evaluated in terms of mass-normalized genotoxicity (SCEs/mg PM_2.5), that represents the genotoxic potency of particles, and air volume-normalized genotoxicity (SCEs/m³ air), that reflects the inhalation risk for people working or spending much time in these microenvironments. Correlation and linear regression analyses were further employed in order to investigate the potential relationships between genotoxicity and the water-soluble concentrations of PM_2.5-bounded heavy metals. According to the results, the highest mass-normalized genotoxicity values were found for PM_2.5 from the photocopying center, whereas the highest air volume-normalized genotoxicity was found in tavern-2. Significant positive correlations between the genotoxicity and water-soluble metals were derived, highlighting the role that heavy metals play in the genotoxicity of indoor PM_2.5. Among the targeted metals, Zn and Pb were found to be good predictors of the genotoxicity of water-soluble PM_2.5.

Cooperative Noncovalent Interactions Lead to a Highly Diastereoselective Sulfonyl-Directed Fluorination of Steroidal α,β-Unsaturated Hydrazones

A series of steroidal α,β-unsaturated hydrazones is presented whose behavior and reactivity are governed by various types of weak C-H hydrogen bonds. Several interesting features in a representative X-ray crystal structure and ¹H NMR spectrum are examined that provide evidence for a unique bifurcated intramolecular C-H interaction. Moreover, these steroid derivatives undergo functionalization in the form of a highly regio- and stereoselective fluorination; the sulfonyl oxygen atoms are proposed to direct the fluorinating reagent through C-H hydrogen bonds.

Sister chromatid exchange assay as a predictor of tumor chemoresponse

Sister Chromatid Exchanges (SCEs) are known to enhance as a consequence of exposure to various mutagenic agents and appear to indicate DNA damaging effects and/or subsequent repair by homologous recombination (HR). DNA damage plays an interesting role in the majority of mechanisms underlying the effects of antitumor drugs, since the genetic activity of the plethora of these agents is due to their ability to damage the DNA. The DNA-effects of antitumor agents towards normal cells (genotoxicity) are great drawbacks of antitumor therapy and are connected to important adverse health effects in cancer patients undergoing chemotherapy. On the other hand, failure of chemotherapy in many cases is due to the DNA repair ability which cancer, like normal cells, also possess. As both DNA repair and genotoxic exposure are expected to vary among patients, correlating SCEs frequencies with only individual repair capacity may be feasible to predict. Cancer risk has not been observed to be associated with high SCEs levels. Since the administration of effective antitumor drugs with limited adverse effects is of great importance in the success of anticancer therapy, a lot of interest has been directed toward the development of methods and approaches that would enable the correct selection of appropriate drugs prior to the initiation of therapy on an individual basis. To this effect, more than 30 years ago, an investigation of the ability of the in vitro and the in vivo SCEs-assay to predict the in vitro and in vivo sensitivity of tumor cells to newly synthesized drugs or to those already in use began. In this short review a critical appraisal of the SCEs-assay as an important biomarker used for predicting cancer chemo-response as well as a summary of the key findings from several studies published within the last 20 years in this field is performed.

The cytogenetic action of ifosfamide, mesna, and their combination on peripheral rabbit lymphocytes: an in vivo/in vitro cytogenetic study

Ifosfamide (IFO) is an alkylating nitrogen mustard, administrated as an antineoplasmic agent. It is characterized by its intense urotoxic action, leading to hemorrhagic cystitis. This side effect of IFO raises the requirement for the co-administration with sodium 2-sulfanylethanesulfonate (Mesna) aiming to avoid or minimize this effect. IFO and Mesna were administrated separately on rabbit's lymphocytes in vivo, which were later developed in vitro. Cytogenetic markers for sister chromatid exchanges (SCEs), proliferation rate index (PRI) and Mitotic Index were recorded. Mesna's action, in conjunction with IFO reduces the frequency of SCEs, in comparison with the SCEs recordings obtained when IFO is administered alone. In addition to this, when high concentrations of Mesna were administered alone significant reductions of the PRI were noted, than with IFO acting at the same concentration on the lymphocytes. Mesna significantly reduces IFO's genotoxicity, while when administered in high concentrations it acts in an inhibitory fashion on the cytostatic action of the drug.