Halogenated hydrocarbon environmental pollution: the special case of halogenated anesthetics

Comparison of genotoxicity of sevoflurane and isoflurane in human lymphocytes studied in vivo using the comet assay

In the present paper, we report data on the possible genotoxic properties of two inhalation anaesthetics--sevoflurane (SVF) and isoflurane (ISF) - in peripheral blood lymphocytes of patients before, during and after anaesthesia as compared to an unexposed control group. Both anaesthetics were evaluated for genotoxic activity using the comet assay. The exposed groups consisted of 24 ASA grades 1-2 unpremedicated patients (aged 20-66 years, anaesthetized 115-162 min for elective lower abdominal surgery), while the control group consisted of 12 healthy individuals. After induction of anaesthesia (thiopenthone sodium 5-7 mg/kg, fentanyl citrate 0.1mg and vecuronium bromide 0.1mg/kg), anaesthesia was maintained with inhalation of SVF 1-1.5% (n=12) or ISF 1-1.5% (n=12) in oxygen-air mixture. Venous blood samples were obtained before the induction of anaesthesia, at 60 and 120 min of anaesthesia and on the first, third and fifth days following anaesthesia. The comet assay detects DNA damage which includes strand breaks and alkaline labile sites induced directly by genotoxic agents as well as DNA degradation due to cell death. One hundred cells from each sample were examined and graded as no tailed, short and long tailed nuclei. The mean comet response was not different between controls and patients before anaesthesia. However, similar significant increases were observed in the mean comet response in blood sampled from patients at 60 (36.5+/-11.2, 37.8+/-12.1), or 120 min (53.1+/-17.1, 50.0+/-12.2) of anaesthesia and on the first day (37.8+/-15.1, 35.2+/-15.7) after anaesthesia in SVF and ISF treated groups, respectively. Removal of the DNA damage was observed after the third day of anaesthesia and the repair was completed within 5 days. The DNA damage detected in lymphocytes of patients during anaesthesia with SVF or ISF showed similar results as demonstrated by an increased mean comet migration at 120 min of anaesthesia and the cells were able to repair the induced DNA damage completely on the fifth postoperative day.

DNA damage evaluated by the alkaline comet assay in lymphocytes of humans anaesthetized with isoflurane

In the present paper, we report data on the possible DNA damage, induced in vivo by isoflurane using the alkaline single cell gel electrophoresis technique (SCGE-comet assay) in patients before/after anaesthesia and in control group. Twelve patients, aged 22-66 years old, were anaesthetized for elective abdominal surgery with isoflurane in oxygen for 120-162 min (mean: 133.2 min). Venous blood samples were obtained from the patients before the induction of anaesthesia, at 60 and 120 min of anaesthesia and on the first, third and fifth following days of anaesthesia. SCGE was examined in 100 cells from each specimen graded as undamaged, intermediate and tailed nuclei. The number of undamaged nucleus was almost same in control and in patients before anaesthesia. However, significant differences were observed in proportion of undamaged, intermediate and tailed nucleus of patients at 60 and 120 min of anaesthesia and on the first day. DNA damage started to return to normal rates after the third day of anaesthesia and were almost identical with the rates of control group five days later.

Effects of isoflurane on the DNase I activity in an isolated enzyme preparation and on the DNase I-G actin complex

Effects of isoflurane on the DNase I activity in an isolated enzyme preparation and in the DNase I-globular (G) actin complex were investigated. DNase I, DNase I-G actin complex, and G actin were exposed to various (0.2-4.0 vol%) isoflurane concentrations for 180 min. Thereafter, DNase I activity was determined. DNase I activity was inhibited in relation to time and concentration of isoflurane exposure. At concentrations ranging from 0.2 to 1.0 vol% of isoflurane inactive DNase I was activated in the DNase I-G actin complex. The DNase I inhibitor G actin showed a reduced capability to inhibit DNase I following isoflurane exposure. Albumin can inhibit the DNase I inactivation possibly by competition in the reactions between DNase I/albumin and isoflurane. After exposure to isoflurane the absorption maximum of DNase I was identical with the absorption maximum of heat-denatured DNase I. The results suggest a mechanism by which isoflurane may affect DNA in an indirect way at concentrations to which the patient is exposed during clinical anesthesia.