The induction of chromosomal abnormalities by inhalational anaesthetics

Potential Increased Risk of Trisomy 18 Observed After a Fertilizer Warehouse Fire in Brazos County and TX

Background: In this paper, we aimed to investigate the potential impacts of a fire accident in a fertilizer warehouse on chromosomal anomalies, including Trisomy 21 (T21) and Trisomy (T18) among pregnancies in Brazos County, Texas. We conducted an observational study in Brazos County, TX, with all patients of T18 and T21 cases in the live births in Brazos County between 2005–2014. The prevalence of T18 and T21 before, during, and after the accident in Brazos County were calculated and compared. The Standardized Morbidity Ratio (SMR) was applied to compare the prevalence of T18 and T21 in Brazos County to the statewide prevalence in Texas after adjusting for maternal race and age. Compared with statewide risk, the risk of T18 during the impacted years in Brazos county was found to be significantly higher (SMR = 5.0, 95% Confidence Interval(CI): 2.19–9.89), while there was no significant difference before (SMR = 0.77, 0.13–2.54) and after the accident (SMR = 0.71, 0.12–2.36). However, the prevalence of T21 during the impacted years was not significantly different from those before or after the accident. This study conclusively suggests that this fertilizer fire may be related to the increased prevalence of T18 in Brazos County, though the findings warrant further investigation.

Cytogenetic assays for mitotic poisons. The grasshopper embryo system for volatile liquids

The present study demonstrates the usefulness of grasshopper (Melanoplus sanguinipes) embryos for detecting mitotic arrest and anaphase abnormalities induced by volatile liquids. Eight compounds were tested with this system. Embryos in vivo (intact chorions) were suspended in sealed chambers and the agents, in various amounts, were placed on the bottom of the chambers. The agents, after evaporation, filled the ambient air in which the embryos respired. After a period of exposure, individual embryos were fixed for squash preparations to determine the mitotic index (MI) and the ratio of anaphases to metaphases (A/M). If an agent completely arrested mitosis at metaphase, the A/M ratio would be zero and the MI would be elevated if the agent does not prevent interphase cells from entering mitosis. Two common organic solvents, benzene and toluene, and two common anesthetics, halothane and chloroform, were found to be potent mitotic arrestants in the present system. Colchicine-like mitoses (c-mitoses) were observed in embryos after treatment of the above four agents; all of these agents except toluene were found to induce an accumulation of c-mitoses. Amyl acetate, 95% ethanol, deionized water, and camphor (in 10% ethanol) failed to show mitosis-arresting effects on the embryos. Abnormal anaphases with lagging chromosomes and multipolar spindles were observed in embryos which showed partial metaphase block after exposure to concentrations of benzene lower than that required for a complete block. Benzene, toluene, halothane, and chloroform have been implicated as teratogens and carcinogens, but are negative as mutagens, clastogens, and SCE inducers. Thus, the carcinogenic activity of these compounds appears to result from their action on cell division mechanisms.

Vicia cytogenetic tests for environmental mutagens. A report of the U.S. Environmental Protection Agency Gene-Tox Program

Vicia root-tip mitotic and pollen mother-cell meiotic tests are two major kinds of cytogenetic tests for environmental mutagens. According to the present review, 81 of 85 earlier studies used mitotic tests to determine the frequencies of chromosome or chromatid aberrations and/or sister-chromatid exchange from root-tip meristematic cells; only 4 used meiotic tests to determine the frequencies of chromosome aberration from pollen mother cells. Treatment of root-tip meristem can be done by allowing the newly germinated roots to absorb the chemical mutagens from a water solution. Pollen mother cells can be treated by spraying the solution or pipetting the liquid over the flower buds. After an appropriate recovery time, the samples are fixed and stained, and the slides are prepared for metaphase or anaphase figures for scoring aberration frequencies. Slides for meiotic tests are prepared for metaphase I and/or Anaphase I stages for scoring chromosome aberration frequencies. Results of both cytogenetic tests should be expressed in terms of number of breaks per cell or per 100 cells. Test results of 76 chemicals from 32 classes in this review indicate that the Vicia root-tip mitotic test is reliable, efficient, and relatively inexpensive. These results also reveal that antibiotics are most frequently studied, followed by alkyl sulfones, pyrimidine, and purine derivatives. Of all the agents studied through root-tip mitotic tests, about 90% gave positive responses; antibiotics (phleomycin and bleomycin) had very high mutagenicity (less than 1 ppm gave positive response).

DNA and chromosome alterations in lymphocytes of operating room personnel and in patients before and after inhalation anaesthesia

In order to evaluate the possible genotoxic effects of inhalation anaesthetics, the frequency of sister chromatid exchanges and chromosome aberrations was studied in peripheral lymphocytes of control subjects, operating room personnel and patients before and after inhalation anaesthesia during orthopaedic operations. In the patients, the frequency of DNA breaks was studied as well. None of the genotoxic parameters showed an increase which could be related to anaesthetic exposure. The frequency of sister chromatid exchange was very similar in the control and personnel groups, as well as in patients before and after operation. The frequency of chromosome aberrations was unusually low in the control group, whereas the personnel and patient groups showed normal levels of chromosome aberrations which did not differ from previously studied control groups. There was no statistical difference in the frequency of chromosome aberrations or DNA breaks in the patient group after, as compared to before, operation. Smokers were found to have a significantly increased frequency of chromosome gaps compared to nonsmokers, but there was no indication that this difference was related to anaesthetic exposure. The data presented give no indications of genotoxic effects in vivo of inhalation anaesthetics by either occupational exposure to waste anaesthetic gases, or anaesthesia during operation. On the other hand, our present data do not contradict previous data indicating that hospital personnel, irrespective of exposure to inhalation anaesthetics, may have a small average increase of chromosome abnormalities.

Selection and characterization of a varient of murine L5178Y lymphoma resistant to local anesthetics

A varient of murine L5178Y lymphoma resistant to procaine hydrochloride (PH) was selected by exposing the cells to gradual increments of PH in the growth medium until the cell grew exponentially in the presence of 1.5 mM PH. Using cinephotomicrography, it was observed that the majority of cells that initially succumbed to PH failed to undergo successful mitosis. With respect ot chromosomal, cell size distribution and flow microfluorometric analyses, the PH-resistant cells are very similar to a spontaneous tetraploid cell line (R1T) previously cloned. The isolated cells, designated R1/P, were also found to be cross-resistant to analogues of PH, namely, lidocaine, tetracaine and dibucaine. The naturally-occurring tetraploid cell line (R1T) was also found to be more resistant to local anesthetics, although not to the same extent as R1/P cells. Since the enzyme that hydrolyzes procaine appears to be absent in all these lymphoid cell lines, the difference in resistance does not appear to depend on differences in the ability of these cells to remove the agent. It is suggested that an alteration in the structure and/or function of the plasma membrane in R1/P cells have rendered them either less sensitive to the membrane-perturbing effects of the local anesthetics or less permeable to local anesthetics molecules. The ability of local anesthetics to affect membranes and cytoskeleton structures may play a role in the genesis and/or selection of these cell variants.