Modulation of gene expression and inflammation but not DNA damage after sevoflurane anesthesia

This study assessed, for the first time, the expression of the genes hOGG1, TP53, and IL-6 in leukocytes by real-time quantitative polymerase chain reaction in surgical patients before (baseline), during (2 h of anesthesia) and 1 day after sevoflurane anesthesia. Additionally, DNA damage was detected by the comet assay, serum interleukin (IL)-6 was detected by flow cytometry, and differential leukocyte counting was also performed. TP53 and hOGG1 expression was downregulated on the day after anesthesia compared to before anesthesia. However, IL-6 expression did not change, and no DNA damage induction was observed during or after anesthesia. At the systemic level, mild neutrophilia and an increase in IL-6 levels occurred after anesthesia. Our findings suggest that sevoflurane anesthesia downregulates gene expression (hOGG1 and TP53) and contributes to an inflammatory status (increased systemic IL-6 and mild neutrophilia) but is not associated with DNA damage in patients without comorbidities who undergo minor elective surgery.

Different damaging effects of volatile anaesthetics alone or in combination with 1 and 2 Gy gamma-irradiation in vivo on mouse liver DNA: a preliminary study

As the number of radiotherapy and radiology diagnostic procedures increases from year to year, so does the use of general volatile anaesthesia (VA). Although considered safe, VA exposure can cause different adverse effects and, in combination with ionising radiation (IR), can also cause synergistic effects. However, little is known about DNA damage incurred by this combination at doses applied in a single radiotherapy treatment. To learn more about it, we assessed DNA damage and repair response in the liver tissue of Swiss albino male mice following exposure to isoflurane (I), sevoflurane (S), or halothane (H) alone or in combination with 1 or 2 Gy irradiation using the comet assay. Samples were taken immediately (0 h) and 2, 6, and 24 h after exposure. Compared to control, the highest DNA damage was found in mice receiving halothane alone or in combination with 1 or 2 Gy IR treatments. Sevoflurane and isoflurane displayed protective effects against 1 Gy IR, while with 2 Gy IR the first adverse effects appeared at 24 h post-exposure. Although VA effects depend on liver metabolism, the detection of unrepaired DNA damage 24 h after combined exposure with 2 Gy IR indicates that we need to look further into the combined effects of VA and IR on genome stability and include a longer time frame than 24 h for single exposure as well as repeated exposure as a more realistic scenario in radiotherapy treatment.

Does Neuraxial Anesthesia as General Anesthesia Damage DNA? A Pilot Study in Patients Undergoing Orthopedic Traumatological Surgery

The human organism is exposed daily to many endogenous and exogenous substances that are the source of oxidative damage. Oxidative damage is one of the most frequent types of cell component damage, leading to oxidation of lipids, proteins, and the DNA molecule. The predominance of these damaging processes may later be responsible for human diseases such as cancer, neurodegenerative disease, or heart failure. Anesthetics undoubtedly belong to the group of substances harming DNA integrity. The goal of this pilot study is to evaluate the range of DNA damage by general and neuraxial spinal anesthesia in two groups of patients undergoing orthopedic traumatological surgery. Each group contained 20 patients, and blood samples were collected before and after anesthesia; the degree of DNA damage was evaluated by the comet assay method. Our results suggest that general anesthesia can cause statistically significant damage to the DNA of patients, whereas neuraxial anesthesia has no negative influence.

DNA damage effects of inhalation anesthetics in human bronchoalveolar cells

BACKGROUND

The main objective was to evaluate and compare the local genotoxicity of sevoflurane and desflurane in bronchoalveolar cells, while the secondary outcome was to detect systemic oxidative DNA damage. To our knowledge, our study is the first one to evaluate the local effects of inhalation anesthetics in human bronchoalveolar cells in patients.

METHODS

American Society of Anesthesiologists group I-II patients scheduled for lumbar discectomy surgery were enrolled in this randomized prospective study. Patients were randomized to sevoflurane or desflurane for anesthesia maintenance. Bronchoalveolar lavage samples and peripheral blood samples were taken at 2-time points: the first point (baseline, T1); and the second point (postexposure, T2). Final number of 48 samples were the sevoflurane (n = 22) and desflurane (n = 26) groups. Comet assay was applied to examine genotoxic properties. Oxidative DNA damage in plasma was measured with 8-hydroxy-2'-deoxyguanosine (8-OHdG).

RESULTS

T2 values were higher than baseline values in both the desflurane group (tail-length: 66 ± 24, %DNA in tail: 72 ± 60, tail moment: 47.52 ± 14.4; P = .001, P = .005, P = .001, respectively) and the sevoflurane group (tail-length: 58 ± 33, %DNA in tail: 88 ± 80, tail moment: 51.04 ± 26.4; P = .001, P = .012, P = .001, respectively). T2 plasma 8-OHdG levels were also higher than baseline levels in the desflurane group (3.91 ± 0.19 ng/ml vs 1.32 ± 0.20 ng/ml, P = .001) and sevoflurane group (3.98 ± 0.18 ng/ml vs 1.31 ± 0.11 ng/ml, P = .001). There were no differences between the 2 groups in comet parameters and 8-OHdG levels.

CONCLUSION

Our results indicate that both inhalation agents cause DNA damage in the bronchoalveolar cells. Also, we detected increases in plasma 8-OHdG concentrations. Local genotoxicity and systemic oxidized DNA damage were similar in both groups.

Can Sevoflurane Induce Micronuclei Formation in Nasal Epithelial Cells of Adult Patients?

Objective

Volatile anaesthetics can inhibit the bronchociliary clearence in a dose- and time-dependend way. Moreover, they can have potential mutagenic/carcinogenic effects under chronic exposure. A genotoxicity test -micronuclei assay- was carried out in nasal epithelial cells to analyze the genotoxic effect of sevoflurane in adult patients undergoing general anesthesia.

Methods

In this study, micronucleus (MN) assay was conducted using nasal epithelial cells of 37 adult patients (age, 18-65 years) who underwent elective, minor, short surgical procedures under general anaesthesia with sevoflurane. Anaesthesia was induced and maintained using 8% sevoflurane (in 6 L min^-1 of oxygen) and an inspired concentration of 2% in O2-air mixture, respectively. Nasal epithelial samples were collected at three time points: before anaesthesia induction (T1), after recovery from anaesthesia in the postanaesthesia care unit (T2) and on postoperative day 21 (T3).

Results

Sevoflurane significantly increased mean MN (‰) frequencies in nasal epithelial cells at T2 (6.97±2.33) and T3 (6.22±2.47) compared with those at T1 (3.84±1.89) (p<0.001). Similar result were observed for MN frequencies if the patients were analysed with regard to age (>40 or <40 years) or sex.

Conclusion

Short-term administration of sevoflurane anaesthesia induces MN formation in nasal epithelial cells of this patient population. Further studies are required for evaluation of the results. The prolonged administration of volatile anaesthetics in various risk groups and surgical protocols should be conducted for evaluating their safety.

The Fast-Halo Assay for the Detection of DNA Damage

The need for express screening of the DNA damaging potential of chemicals has progressively increased over the past 20 years due to the wide number of new synthetic molecules to be evaluated, as well as the adoption of more stringent chemical regulations such as the EU REACH and risk reduction politics. In this regard, DNA diffusion assays such as the microelectrophoretic comet assay paved the way for rapid genotoxicity testing. A more significant simplification and speeding up of the experimental processes was achieved with the fast halo assay (FHA) described in the present chapter. FHA operates at the single cell level and relies on radial dispersion of the fragments of damaged DNA from intact nuclear DNA. The fragmented DNA is separated by diffusion in an alkaline solvent and is stained, visualized, and finally quantified using computer-assisted image analysis programs. This permits the rapid assessment of the extent of DNA breakage caused by different types of DNA lesions. FHA has proven to be sensitive, reliable, and flexible. This is currently one of the simplest, cheapest, and quickest assays for studying DNA damage and repair in living cells. It does not need expensive reagents or electrophoretic equipment and requires only 40 min to prepare samples for computer-based quantification. This technique can be particularly useful in rapid genotoxicity assessments and in high-throughput genotoxicity screenings.

Alkaline nuclear dispersion assays for the determination of DNA damage at the single cell level

Over the past three decades the development of methods for visualizing at the cell level the extent of DNA breakage significantly contributed to genotoxicity testing: their availability greatly improved the knowledge in the field of genetic toxicology. These procedures are based on the separation and visualization of DNA fragments resulting from cleavage of nuclear DNA. The separation process can be obtained either electrically (comet assay, linear migration of DNA fragments) or chemically (alkaline dispersion assays, radial diffusion of DNA fragments). Once separated and stained, intact and fragmented DNA can be observed with fluorescence or light microscope. Appropriate computer-assisted image analysis allows quantitative determination of the extent of DNA breakage. These procedures have been proven to be sensitive, flexible, and reliable, and, as compared to former methods, they are simpler, are less time and money consuming, and have the unique capability of detecting DNA damage at the single cell level. This last feature has the additional advantage of allowing the identification of cellular subpopulations characterized by different sensitivity to the damaging agent. The fast halo assay (FHA) is currently the simplest and quickest nuclear dispersion assay; recent modifications of FHA have further improved the assay and pave the way to a full exploitation of its analytical potential. In this chapter the development, procedures, applications, and limits of these dispersion assays, with a particular focus on FHA, will be illustrated.

Sevoflurane reduces clinical disease in a mouse model of multiple sclerosis

Background

Inhalational anesthetics have been shown to influence T cell functions both in vitro and in vivo, in many cases inducing T cell death, suggesting that exposure to these drugs could modify the course of an autoimmune disease. We tested the hypothesis that in mice immunized to develop experimental autoimmune encephalomyelitis (EAE), a well established model of multiple sclerosis (MS), treatment with the commonly used inhalational anesthetic sevoflurane would attenuate disease symptoms.

Methods

C57Bl6 female mice were immunized with myelin oligodendrocyte glycoprotein (MOG) peptide residues 35 to 55 to induce a chronic demyelinating disease. At day 10 after immunization, the mice were subjected to 2 h of 2.5% sevoflurane in 100% oxygen, or 100% oxygen, alone. Following treatment, clinical scores were monitored up to 4 weeks, after which brain histology was performed to measure the effects on astrocyte activation and lymphocyte infiltration. Effects of sevoflurane on T cell activation were studied using splenic T cells isolated from MOG peptide-immunized mice, restimulated ex vivo with MOG peptide or with antibodies to CD3 and CD28, and in the presence of different concentrations of sevoflurane. T cell responses were assessed 1 day later by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay for proliferation, lactate dehydrogenase (LDH) release for cell death, and inflammatory activation by production of interleukin (IL)-17 and interferon (IFN)γ.

Results

Clinical scores in the oxygen-treated group increased until day 28 at which time they showed moderate to severe disease (average clinical score of 2.9). In contrast, disease progression in the sevoflurane-treated group increased to 2.1 at day 25, after which it remained unchanged until the end of the study. Immunohistochemical analysis revealed reduced numbers of infiltrating leukocytes and CD4⁺ cells in the CNS of the sevoflurane-treated mice, as well as reduced glial cell activation. In splenic T cells, low doses of sevoflurane reduced IFNγ production, cell proliferation, and increased LDH release.

Conclusions

These results are the first to show attenuation of EAE disease by an inhaled anesthetic and are consistent with previous reports that inhaled anesthetics, including sevoflurane, can suppress T cell activation that, in the context of autoimmune diseases such as MS, could lead to reduced clinical progression.

Assessment of individual susceptibility to baseline DNA and cytogenetic damage in a healthy Turkish population: evaluation with lifestyle factors

BACKGROUND

Cytogenetic biomarkers are most frequently used well-established endpoints in human population studies with their sensitivity for measuring exposure to genotoxic agents. They have an important role as early predictors of cancer risk. Identification of individual genotypes of metabolic gene polymorphisms helps to understand the modulation of cancer susceptibility by environmental exposures, such as cigarette smoking and other lifestyle factors.

AIM

To evaluate individual susceptibility to chemicals, we determined individual DNA damage related to glutathione S-transferase (GST) genotypes (GSTM1, GSTT1, and GSTP1) in a Turkish population.

METHODS

Peripheral blood lymphocytes (PBL) and DNA samples of 127 subjects were analyzed for the presence of DNA damage, using single-cell gel electrophoresis (the Comet assay), and for cytogenetic parameters (chromosomal aberrations [CAs], bleomycin-induced CA, and a cytokinesis-blocked micronucleus assay), and the polymerase chain reaction/restriction fragment length polymorphism method, respectively.

RESULTS

Individuals carrying a GSTT1-null allele showed higher frequencies of CA and micronucleus (MN) (p=0.026, p=0.003, respectively), whereas the GSTM1-null and GSTP1 mutant genotypes did not show any differences in cytogenetic parameters. Our findings demonstrated that none of the lifestyle factors (smoking, alcohol drinking, dietary habits, vitamin intake, and physical activity), except for vitamin intake (p=0.002), were significantly associated with the studied cytogenetic parameters.

CONCLUSION

Our results suggest that the GSTT1 gene polymorphism may influence the baseline cytogenetic frequency in a healthy population.

Determination of DNA damage after exposure to inhalation anesthetics in human peripheral lymphocytes and sperm cells in vitro by comet assay

In this study, genotoxic activities of four halogenated anesthetics (halothane, isoflurane, sevoflurane and desflurane) were investigated in human peripheral blood lymphocytes (PBLs) and sperm cells in vitro by alkaline comet assay. For this purpose, sperm or lymphocyte suspension was exposed to different concentrations (0.1 mM, 1 mM, 10 mM and 100 mM) of anesthetic agents and 1% dimethyl sulfoxide (DMSO) or phosphate-buffered saline (PBS) as controls. The DNA strand breaks as well as alkali-labile sites were measured as percentage tail intensity with comet assay. The results of this study demonstrate that all analyzed drugs were capable of inducing DNA damage on PBLs in a dose-dependent manner in vitro. However, the results in sperm cells were slightly different since we did not observe any genotoxic effect for desflurane in any of the exposure doses, and the genotoxic effect of halothane was not dose dependent. This experimental study points out to the presence of DNA damage after exposure to halogenated anesthetics in both PBLs and sperm cells, although this effect seems to be higher in PBLs.

DNA damage in patients who underwent minimally invasive surgery under inhalation or intravenous anesthesia

Recent studies have demonstrated the genotoxicity of anesthetics in patients who have undergone surgery and in personnel who are occupationally exposed to anesthetics. However, these findings are controversial. Herein, we used the comet assay (single-cell gel electrophoresis) to investigate the genotoxic effects of two volatile compounds [isoflurane (ISF) and sevoflurane (SVF)] that are used in inhalation anesthesia, and of one intravenous (iv) anesthetic compound [propofol (PF)]. The groups consisted of 45 patients who underwent minimally invasive surgery that lasted at least 2h. Patients were classified as physical status I using the criteria of the American Society of Anesthesiologists (ASA) and were randomly allocated to receive ISF, SVF or PF anesthesia. Venous blood samples were collected at three time points as follows: before the premedication and the induction of anesthesia (T(0)); 2h after the beginning of anesthesia (T(1)); and on the day following surgery (T(2)). DNA damage (strand breaks and alkali-labile sites) was evaluated in peripheral blood lymphocytes. For each patient, one hundred nucleoids were analyzed per time point using a semi-automated image system. Patients did not differ with respect to their demographic characteristics, the duration of surgery, or the total doses of intraoperative drugs. The amount of DNA damage was not different among the three groups before anesthesia (T(0)). No statistically significant (p>0.05) increase in DNA damage was detected during (T(1)) or after anesthesia (T(2)) using three different protocols (ISF, SVF or PF). In conclusion, general anesthesia with inhaled ISF and SVF or iv PF did not induce DNA strand breaks or alkali-labile sites in peripheral lymphocytes. Therefore, our results show that the genotoxic risk of these anesthetics, for healthy patients undergoing minimally invasive otorhinological surgery, is low or even absent.

Genotoxic effects of anesthetic agents: an update

INTRODUCTION

Exposure to anesthetics in the health environment may entail a health risk for patients and operating room personnel. Knowing the effects of anesthetic agents on genetic material could be a valuable basic support for anesthesia care providers to improve treatment performance, increase patient safety and reduce the risks for patients and staff in the operating room.

AREAS COVERED

Relevant literature was identified using MEDLINE, CINAHL® and Cochrane Library databases. Over 200 abstracts for articles published from 1980 to 2010 were examined. Original articles were reviewed and relevant citations from these articles were also considered.

EXPERT OPINION

Despite some conflicting results, the current available data indicate that exposure to anesthetics, especially nitrous oxide and halogenated agents, is associated with general and genotoxic risks, whereas intravenous agents, such as propofol and its metabolites are not associated with genotoxic effects. Moreover, given that different anesthetic drugs are used in combination it is, thus, very difficult to understand whether the observed effects or absence of effects are due to an individual agent action or linked to a synergy action of different anesthetics involved. Further clinical and experimental evidence is warranted.

Evaluation of DNA damage in construction-site workers occupationally exposed to welding fumes and solvent-based paints in Turkey

In this study, the comet assay was used to evaluate whether welding fume and solvent base paint exposure led to DNA damage in construction-site workers in Turkey. The workers (n = 52) were selected according to their exposure in the construction site and controls (n = 26) from the general population, with no history of occupational exposure. The alkaline comet assay, a standard method for assessing genotoxicity, has been applied in peripheral lymphocytes of all subjects. The mean percentages of DNA in tail (%DNA(T)) of each group were evaluated, including the comparisons between smokers in each different group and the duration of exposure. Significant increase in the mean %DNA(T) (p < 0.01) was observed in all exposed subjects (12.34 ± 2.05) when compared with controls (6.64 ± 1.43). Also %DNA(T) was significantly high (p < 0.01) in welders (13.59 ± 1.89) compared with painters (11.10 ± 1.35). There was a statistical meaningful difference in % DNA(T) between control and exposed smokers. Our findings indicate that exposure to welding fumes and paints induce genotoxic effect in peripheral lymphocytes, indicating a potential health risk for workers. Therefore, to ensure maximum occupational safety, biomonitoring is of great value for assessing the risk for construction workers.