Does 'Dry Hit' vaping of vitamin E acetate contribute to EVALI? Simulating toxic ketene formation during e-cigarette use.

Vitamin E acetate (VEA) is strongly linked to the outbreak of electronic-cigarette or vaping product use-associated lung injury (EVALI). It has been proposed that VEA decomposition to ketene-a respiratory poison that damages lungs at low ppm levels-may play a role in EVALI. However, there is no information available on the temperature at which VEA decomposes and how this correlates with the vaping process. We have studied the temperature-dependent kinetics of VEA decomposition using quantum chemical and statistical mechanical modelling techniques, developing a chemical kinetic model of the vaping process. This model predicts that, under typical vaping conditions, the use of VEA contaminated e-cigarette products is unlikely to produce ketene at harmful levels. However, at the high temperatures encountered at low e-cigarette product levels, which produce 'dry hits', ketene concentrations are predicted to reach acutely toxic levels in the lungs (as high as 30 ppm). We therefore hypothesize that dry hit vaping of e-cigarette products containing VEA contributes to EVALI.

Potential for release of pulmonary toxic ketene from vaping pyrolysis of vitamin E acetate.

A combined analytical, theoretical, and experimental study has shown that the vaping of vitamin E acetate has the potential to produce exceptionally toxic ketene gas, which may be a contributing factor to the upsurge in pulmonary injuries associated with using e-cigarette/vaping products. Additionally, the pyrolysis of vitamin E acetate also produces carcinogen alkenes and benzene for which the negative long-term medical effects are well recognized. As temperatures reached in vaping devices can be equivalent to a laboratory pyrolysis apparatus, the potential for unexpected chemistries to take place on individual components within a vape mixture is high. Educational programs to inform of the danger are now required, as public perception has grown that vaping is not harmful.

Enhanced stable production of ethylene in photosynthetic cyanobacterium Synechococcus elongatus PCC 7942.

Ethylene is a volatile alkene which is used in large commercial scale as a precursor in plastic industry, and is currently derived from petroleum refinement. As an alternative production strategy, photoautotrophic cyanobacteria Synechocystis sp. PCC 6803 and Synechococcus elongatus PCC 7942 have been previously evaluated as potential biotechnological hosts for producing ethylene directly from CO2, by the over-expression of ethylene forming enzyme (efe) from Pseudomonas syringae. This work addresses various open questions related to the use of Synechococcus as the engineering target, and demonstrates long-term ethylene production at rates reaching 140 µL L-1 h-1 OD750-1 without loss of host vitality or capacity to produce ethylene. The results imply that the genetic instability observed earlier may be associated with the expression strategies, rather than efe over-expression, ethylene toxicity or the depletion of 2-oxoglutarate-derived cellular precursors in Synechococcus. In context with literature, this study underlines the critical differences in expression system design in the alternative hosts, and confirms Synechococcus as a suitable parallel host for further engineering.

Toxicity study of DE-EDCP as a potential drug for cancer therapy: Toxicity profile of DE-EDCP.

It was reported that novel O, O'-diethyl-(S, S)-ethylenediamine- N, N'-di-2-(3-cyclohexyl) propanoate dihydrochloride (DE-EDCP) displayed in vitro antiproliferative activity on several human and mouse cancer cell lines, which was comparable to that of the prototypical anticancer drug cisplatin. In order to reveal its toxicity profile, acute and repeated-dose toxicity studies were performed in Naval Medical Research Institute (NMRI) Han mice. The intravenous LD50 values of DE-EDCP were found to be 95.3 and 101.3 mg/kg body weight in female and male mice, respectively. In the subacute toxicity study, DE-EDCP was administered intravenously at the doses of 15, 25, and 40 mg/kg/day for a period of 28 days. There were no adverse effects on general condition, growth, feed and water consumption, and hematological parameters. There was a significant increase in urea and alanine aminotransferase in female mice and aspartate aminotransferase and alkaline phosphatase in both genders in 40 mg/kg/day dose-treated group. The histopathological changes confined to the liver and kidney, but in other organs were not found. Satellite group revealed that changes in the kidney and liver were less pronounced, suggesting their reversibility. Interactions with DNA could also be of importance for understanding DE-EDCP toxic side effects. Hyperchromic effect obtained with ultraviolet-visible, suggested electrostatic interactions between DE-EDCP and calf thymus DNA. The toxicity testing of DE-EDCP was conducted to predict human outcomes.

The effect of two bromfenvinphos impurities: BDCEE and ß-ketophosphonate on oxidative stress induction, acetylcholinesterase activity, and viability of human red blood cells.

Numerous research works have shown that synthesis of pesticides leads to the formation of impurities that may substantially enhance pesticide toxicity. In this study, the effect of manufacturing impurities of pesticide bromfenvinphos (BFVF) such as 1-bromo-2-(2,4-dichlorophenyl)-2-ethoxy ethene (BDCEE) and diethyl [2-(2,4-dichlorophenyl)-2-oxo-ethyl] phosphonate (ß-ketophosphonate) on human erythrocytes, being significantly exposed to xenobiotics has been studied. The cells were treated with the compounds studied in the concentrations ranging from 0.1 µM to 250 µM for 4 h. In order to assess the effect of BDCEE and ß-ketophosphonate on red blood cells hemolytic changes, changes in cell size (FSC parameter) and oxidation of hemoglobin were studied. Moreover, alterations in reactive oxygen species (ROS) formation, reduced glutathione (GSH) level and acetylcholinesterase (AChE) activity were determined. BDCEE induced an increase in ROS level and caused strong oxidation of hemoglobin as well as a slight change in erythrocytes size and hemolysis, while it did not change GSH level and AChE activity. ß-ketophosphonate has not been shown to affect most parameters studied, but it strongly reduced AChE activity. Because changes in the parameters examined were noted at low concentrations of BFVF impurities (5-250 µM), those substances should not negatively affect on red blood cells of humans environmentally exposed to this pesticide.

Methods for enhancing cyanobacterial stress tolerance to enable improved production of biofuels and industrially relevant chemicals.

Cyanobacteria are photosynthetic prokaryotes that can fix atmospheric CO2 and can be engineered to produce industrially important compounds such as alcohols, free fatty acids, alkanes used in next-generation biofuels, and commodity chemicals such as ethylene or farnesene. They can be easily genetically manipulated, have minimal nutrient requirements, and are quite tolerant to abiotic stress making them an appealing alternative to other biofuel-producing microbes which require additional carbon sources and plants which compete with food crops for arable land. Many of the compounds produced in cyanobacteria are toxic as titers increase which can slow growth, reduce production, and decrease overall biomass. Additionally, many factors associated with outdoor culturing of cyanobacteria such as UV exposure and fluctuations in temperature can also limit the production potential of cyanobacteria. For cyanobacteria to be utilized successfully as biofactories, tolerance to these stressors must be increased and ameliorating stress responses must be enhanced. Genetic manipulation, directed evolution, and supplementation of culture media with antioxidants are all viable strategies for designing more robust cyanobacterial strains that have the potential to meet industrial production goals.

A physiologically based toxicokinetic model for inhaled ethylene and ethylene oxide in mouse, rat, and human.

Ethylene (ET) is the largest volume organic chemical. Mammals metabolize the olefin to ethylene oxide (EO), another important industrial chemical. The epoxide alkylates macromolecules and has mutagenic and carcinogenic properties. In order to estimate the EO burden in mice, rats, and humans resulting from inhalation exposure to gaseous ET or EO, a physiological toxicokinetic model was developed. It consists of the compartments lung, richly perfused tissues, kidneys, muscle, fat, arterial blood, venous blood, and liver containing the sub-compartment endoplasmic reticulum. Modeled ET metabolism is mediated by hepatic cytochrome P450 2E1, EO metabolism by hepatic microsomal epoxide hydrolase or cytosolic glutathione S-transferase in various tissues. EO is also spontaneously hydrolyzed or conjugated with glutathione. The model was validated on experimental data collected in mice, rats, and humans. Modeled were uptake by inhalation, wash-in-wash-out effect in the upper respiratory airways, distribution into tissues and organs, elimination via exhalation and metabolism, and formation of 2-hydroxyethyl adducts with hemoglobin and DNA. Simulated concentration-time courses of ET or EO in inhaled (gas uptake studies) or exhaled air, and of EO in blood during exposures to ET or EO agreed excellently with measured data. Predicted levels of adducts with DNA and hemoglobin, induced by ET or EO, agreed with reported levels. Exposures to 10000 ppm ET were predicted to induce the same adduct levels as EO exposures to 3.95 (mice), 5.67 (rats), or 0.313 ppm (humans). The model is concluded to be applicable for assessing health risks from inhalation exposure to ET or EO.

Results from a round robin test for the ecotoxicological evaluation of construction products using two leaching tests and an aquatic test battery.

A European round robin test according to ISO 5725-2 was conceptually prepared, realised, and evaluated. The aim was to determine the inter-laboratory variability of the overall process for the ecotoxicological characterization of construction products in eluates and bioassays. To this end, two construction products BAM-G1 (granulate) and HSR-2 (roof sealing sheet), both made of EPDM polymers (rubber), were selected. The granular construction product was eluted in a one stage batch test, the planar product in the Dynamic Surface Leaching test (DSLT). A total of 17 laboratories from 5 countries participated in the round robin test: Germany (12), Austria (2), Belgium (1), Czech Republic (1) and France (1). A test battery of four standardised ecotoxicity tests with algae, daphnia, luminescent bacteria and zebrafish eggs was used. As toxicity measures, EC50 and LID values were calculated. All tests, except the fish egg test, were basically able to demonstrate toxic effects and the level of toxicity. The reproducibility of test results depended on the test specimens and the test organisms. Generally, the variability of the EC50 or LID values increased with the overall level of toxicity. For the very toxic BAM-G1 eluate a relative high variability of CV = 73%-110% was observed for EC50 in all biotests, while for the less toxic HSR-2 eluate the reproducibility of EC50 varied with sensitivity: it was very good (CV = 9.3%) for the daphnia test with the lowest sensitivity, followed by the algae test (CV = 36.4%). The luminescent bacteria test, being the most sensitive bioassay for HSR-2 Eluate, showed the highest variability (CV = 74.8%). When considering the complex overall process the reproducibility of bioassays with eluates from construction products was acceptable.

Health- and vegetative-based effect screening values for ethylene.

Ethylene (ET) is ubiquitous in the environment and is produced both naturally and due to anthropogenic sources. Interestingly, the majority of ambient ET contribution is from natural sources and anthropogenic sources contribute only a minor portion. While microbes and plants naturally produce a large amount of ET, mammals are reported to produce only a small amount of ET endogenously. Anthropogenic sources of ET include the combustion of gas, fuel, coal and biomass. ET is also widely used as an intermediate to make other chemicals and products and is also used for controlled ripening of fruits and vegetables. Although, a review of human and laboratory animal studies indicate ET to be relatively non-toxic, there is concern about the potential toxicity of ET because ET is metabolically converted to ethylene oxide (EtO). EtO has been classified to be carcinogenic to human by the inhalation route by the International Agency for Research on Cancer (IARC) cancer. ET, however, has been classified as a Group 3 chemical which indicates it is not classified as a human carcinogen by IARC. Several studies have reported ET to cause adverse effects to plant species (vegetation effects) at concentrations that are not adverse to humans. Therefore, the Texas Commission of Environmental Quality (TCEQ) conducted detailed health and welfare (odor and vegetation) based assessments of ET to develop both health and vegetative based toxicity factors in 2008 in accordance with TCEQ guidelines. The health assessment based on well-conducted animal toxicity studies resulted in identification of higher points of departures and subsequently higher effect screening levels (ESLs) that were more than a magnitude higher than the threshold adverse effect level for vegetative effects for ET. Further, based on a weight-of-evidence evaluation of potential mutagenic and carcinogenic mode-of-actions for ET it appears the metabolic conversion of ET to EtO is of insufficient magnitude to cause concern of potential cancer risk. Therefore, the short-term ESL for air permit reviews and air monitoring evaluations is the vegetation-based ESL of 1200 ppb as it is more than a magnitude lower than the health-based acute ESL of 150,000 ppb. Similar to the acute derivation, the chronic evaluation resulted in the derivation of a chronic vegetation based ESL of 30 ppb that was much lower than the chronic ESL of 1600 ppb. In summary, the TCEQ's acute and chronic ESLs for vegetation will protect the general public from short-term and long-term adverse health and welfare effects. The general public includes children, the elderly, pregnant women, and people with pre-existing health conditions.

Definição do ponto de colheita comercial e da concentração de etileno exógeno visando melhor aproveitamento do potencial comercial e nutricional de bananas da cultivar Thap Maeo / Definition of harvest time and exogenous etilene concentration aiming at the better commercial and nutritional potential of the bananas of the Thap Maeo cultivar

A banana é um fruto consumido no mundo todo e, ao contrário do que acontece na maioria dos países nos quais predomina o grupo Cavendish, uma grande variedade de cultivares são consumidas nas diferentes regiões do Brasil. No entanto, as informações bioquímicas e fisiológicas a respeito das cultivares consumidas no país são ainda restritas e, apesar de serem muito diferentes entre si, são tratadas da mesma maneira na pré e pós-colheita, o que muitas vezes compromete a qualidade do fruto. Diante disso, dois pontos são fundamentais para a obtenção de frutos de melhor qualidade: a definição do ponto de colheita e o tratamento dos frutos com etileno após a colheita. Hoje a colheita é feita em função do diâmetro dos frutos e o tratamento com etileno é o mesmo para todas as cultivares. Porém, frutos com o mesmo diâmetro nem sempre estão no mesmo estágio de maturidade fisiológica e, usualmente, o tratamento pós-colheita feito com etileno, visando o amadurecimento mais rápido e uniforme dos frutos, não segue nenhuma orientação técnica. A consequência da falta de critérios definidos para a colheita e para a aplicação de etileno resulta em bananas com baixa qualidade e com vida-de-prateleira curta. A produção de banana é dificultada pelos problemas fitossanitários que ocorrem nas plantações, incluindo doenças como as Sigatokas Negra e Amarela e o Mal-do-Panamá. Tendo em vista a ameaça que as doenças da bananeira representam e os prejuízos que podem causar, a introdução de cultivares resistentes é a melhor forma para reduzir a pressão desses patógenos sobre a cultura. Por ser resistente às Sigatokas e ao Mal de Panamá este trabalho visou conhecer melhor a cultivar Thap Maeo (Musa acuminata AAB cv. Thap Maeo) que tem como defeito principal uma vida-de-prateleira muito curta. Os objetivos deste trabalho foram: (1) estabelecer o ponto de colheita das bananas da cultivar Thap Maeo utilizando a metodologia da soma de temperatura a que a planta está exposta durante o desenvolvimento dos frutos; (2) estabelecer, a partir da caracterização físico-química dos frutos, o teor ideal de etileno exógeno para promover o amadurecimento uniforme dos frutos e, (3) estudar o balanço hormonal no amadurecimento dos frutos. Em uma primeira etapa foi implantado um experimento de campo para determinar a Temperatura Base e a Idade Fisiológica Máxima para esta cultivar. Estes parâmetros são necessários para o cálculo da idade fisiológica e na determinação do ponto de colheita. Com o término desta etapa, foram realizadas colheitas de frutos em diferentes épocas do ano para confirmar a metodologia usada. Foi possível estabelecer uma metodologia para estimar o ponto de colheita dos frutos de acordo com a estação do ano em que estes se desenvolveram. Para estabelecer o teor ideal de etileno exógeno aplicado na pós-colheita, os frutos foram testados com diferentes concentrações de etileno (0 a 1000 ppm) em dose única. Os resultados indicam que mesmo as menores concentrações de etileno aplicadas promovem o amadurecimento uniforme dos frutos, sem diferenças aparentes entre os tratamentos. Além disso, as análises do perfil de compostos voláteis da polpa indicam que a maior diferença entre o aroma dos tratamentos é entre frutos tratados e não tratados. Os frutos que não foram tratados apresentaram maior quantidade de compostos identificados. Em todas as colheitas realizadas, o período entre o início do amadurecimento e o amadurecimento completo dos frutos foi consideravelmente curto se comparado a bananas do subgrupo Nanica. Para melhor compreender estes resultados, além do etileno, foram quantificados os teores livres dos hormônios ácido indol-3-acético (AIA) e ácido abcísico (ABA). Em comparação com estudos anteriores, com cultivares do subgrupo Nanica, a cultivar Thap Maeo produz mais etileno e ABA durante o amadurecimento, além de apresentar menores teores de AIA quando verde. Estas diferenças hormonais podem explicar o curto período de amadurecimento desta cultivar

Banana is an important staple food. Unlike the world Market, which has only the Cavendish Bananas as export bananas, Brazilian market has many Bananas varieties. However, biochemical and physiological information about these varieties are still scarce and different bananas cultivars are treated the same way in pre or post-harvest, which often affects the quality of the fruit. In this context, two issues are important to reach best fruit quality: definition of harvest time and the exogenous ethylene treatment. Now a day the harvest time is defined by the diameter of the fruits and the ethylene treatment is equal for all cultivars. However, fruits with the same diameter not always are in the same development grade and the post-harvest ethylene treatment, aiming a faster and uniform ripening, does not follow any technical recommendation. The consequences for the lack of criteria in the harvest and for the ethylene treatment might be a low quality and shelf life banana. Banana production is hampered by plant health problems occurring in the production fields, including the diseases such as the Sigatokas and the Panama Wilt. Given the threat of the banana diseases, and the damage they can cause, the introduction of resistant cultivars is the best way to reduce the pressure of these pathogens on this crop. Being resistant to Sigatokas and Panama diseases, this work aimed to know better the cultivar Thap Maeo (Musa acuminata AAB cv. Thap Maeo) whose main defect is a short shelf life. The objectives of this work were: (1) to establish the harvest time of Thap Maeo bananas using the thermal sum techniques, (2) using the physico-chemical characterization of the fruit, establish the ideal concentration of exogenous ethylene to promote uniform ripening of fruits and (3) study the hormonal balance in the fruit ripening. The first step was a field experiment to determine the base temperature and the maximum physiological age. These parameters are used to calculate the thermal sum. The next step was to harvest fruits from different times of the year to confirm the methodology. It was established a methodology to estimate the harvest time according to the season in which the fruit has developed. Five ethylene concentration were tested (0-1000 ppm). Results showed that even the low ethylene concentration applied could promote the uniform ripening of the fruits with no apparent differences between the treatments. Furthermore, the analysis of volatile compounds in the pulp indicate that the major difference between the aroma of treatments is between treated and untreated fruits. The fruits that were not treated showed a higher amount of identified compounds. For all harvested fruits, the period between the ripening start and full ripening of the fruit was short when compared to the Nanica bananas. Levels of the hormones indole-3-acetic acid and abscisic acid, in addition to ethylene, were quantified to better understand these results. Compared to previous studies, with cultivars of Nanica subgroup, the cultivar Thap Maeo produce more ethylene and ABA during ripening, and have lower IAA level in the green stage. These hormonal differences may explain the short maturity period of this cultivar

Ethylene oxide in blood of ethylene-exposed B6C3F1 mice, Fischer 344 rats, and humans.

The gaseous olefin ethylene (ET) is metabolized in mammals to the carcinogenic epoxide ethylene oxide (EO). Although ET is the largest volume organic chemical worldwide, the EO burden in ET-exposed humans is still uncertain, and only limited data are available on the EO burden in ET-exposed rodents. Therefore, EO was quantified in blood of mice, rats, or 4 volunteers that were exposed once to constant atmospheric ET concentrations of between 1 and 10 000 ppm (rodents) or 5 and 50 ppm (humans). Both the compounds were determined by gas chromatography. At ET concentrations of between 1 and 10 000 ppm, areas under the concentration-time curves of EO in blood (µmol × h/l) ranged from 0.039 to 3.62 in mice and from 0.086 to 11.6 in rats. At ET concentrations ≤ 30 ppm, EO concentrations in blood were 8.7-fold higher in rats and 3.9-fold higher in mice than that in the volunteer with the highest EO burdens. Based on measured EO concentrations, levels of EO adducts to hemoglobin and lymphocyte DNA were calculated for diverse ET concentrations and compared with published adduct levels. For given ET exposure concentrations, there were good agreements between calculated and measured levels of adducts to hemoglobin in rats and humans and to DNA in rats and mice. Reported hemoglobin adduct levels in mice were higher than calculated ones. Furthermore, information is given on species-specific background adduct levels. In summary, the study provides most relevant data for an improved assessment of the human health risk from exposure to ET.

Tetraphenylethene-based aggregation-induced emission fluorescent organic nanoparticles: facile preparation and cell imaging application.

Tetraphenylethene-based (TPE) aggregation-induced emission fluorescent organic nanoparticles (FONs) were facilely prepared via Schiff base condensation with ɛ-polylysine (Ply) and subsequent reduction to form stable CN covalent bond. Thus obtained TPE-Ply FONs were characterized by a series of techniques including fluorescent spectroscopy, Fourier transform infrared spectroscopy and transmission electron microscopy. Biocompatibility evaluation and cell uptake behavior of TPE-Ply FONs were further investigated to explore their potential biomedical application. We demonstrated that such FONs showed high water dispersibility, intense fluorescence, uniform morphology (100-200nm) and excellent biocompatibility, making them promising for cell imaging application.

Compounded effects of chlorinated ethene inhibition on ecological interactions and population abundance in a Dehalococcoides - Dehalobacter coculture.

The development of rational and effective engineered bioremediation approaches for sites contaminated with chlorinated solvents requires a fundamental understanding of the factors limiting the in situ activity of dehalorespiring bacteria. Frequently, multiple dehalorespiring bacteria are present at contaminated sites, particularly when bioaugmentation is applied. The ecological interactions between different dehalorespiring populations can-along with hydrodynamic and other environmental factors-affect their activity and thus the rates and extent of dehalorespiration. An integrated experimental and modeling approach was used to evaluate the ecological interactions between two hydrogenotrophic, dehalorespiring strains. A dual Monod model of dehalorespiration provided a good fit to the chlorinated ethene concentrations measured in a coculture of Dehalococcoides mccartyi 195 and Dehalobacter restrictus growing on tetrachloroethene (PCE) and excess H(2) in a continuous-flow reactor. Inhibition of dehalorespiration by chlorinated ethenes was previously observed in cultures containing Dehalococcoides or Dehalobacter strains. Therefore, inhibition coefficients were estimated for Dhc. mccartyi 195 and Dhb. restrictus. The inhibition effects of PCE and TCE on VC dechlorination by Dhc. mccartyi 195, and of VC on PCE and TCE dechlorination by Dhb. restrictus, were compounded when these strains were grown in coculture, and dehalorespiring population abundance and survival could be accurately predicted only by incorporating these complex interactions into the dual Monod model.

Toxicity of brominated volatile organics to freshwater biota.

As part of a larger study investigating the fate and effects of brominated volatile organic compounds (VOCs) in contaminated groundwaters discharging to surface waters, the toxicity of 1,2 dibromoethene (DBE) and 1,1,2-tribromoethene (TriBE) to freshwater aquatic biota was investigated. Their toxicity to bacteria (Microtox(R)), microalgae (Chlorella sp.), cladocerans (Ceriodaphnia dubia), duckweed (Lemna sp.) and midges (Chironomus tepperi) was determined after careful optimization of the test conditions to minimize chemical losses throughout the tests. In addition, concentrations of DBE and TriBE were carefully monitored throughout the bioassays to ensure accurate calculation of toxicity values. 1,2-Dibromoethene showed low toxicity to most species, with concentrations to cause 50% lethality or effect (LC/EC50 values) ranging from 28 to 420 mg/L, 10% lethality or effect (LC/EC10 values) ranging from 18 to 94 mg/L and no-observed-effect concentrations (NOECs) ranging from 22 to 82 mg/L. 1,1,2-Tribromoethene was more toxic than DBE, with LC/EC50 values of 2.4 to 18 mg/L, LC/EC10 values of 0.94 to 11 mg/L and NOECs of 0.29 to 13 mg/L. Using these limited data, together with data from the only other published study on TriBE, moderate-reliability water quality guidelines (WQGs) were estimated from species sensitivity distributions. The proposed guideline trigger values for 95% species protection with 50% confidence were 2 mg/L for DBE and 0.03 mg/L for TriBE. The maximum concentrations of DBE and TriBE in nearby surface waters (3 and 1 microg /L, respectively) were well below these WQGs, so the risk to the freshwater environment receiving contaminated groundwater inflows was considered to be low, with hazard quotients <1 for both VOCs. Environ.

Effects of compressed unsaturated hydrocarbon gases on yeast growth.

The effect of compressed unsaturated hydrocarbon gases on the growth of the yeast Saccharomyces cerevisiae was investigated by microcalorimetry. The growth thermograms showed that unsaturated hydrocarbon gases inhibited yeast growth. As an approach to determining the comparative toxicity of unsaturated hydrocarbon gases, we determined the 50% inhibitory pressure (IP(50)) and the minimum inhibitory pressure (MIP). On the basis of the IP(50) and MIP values, the inhibitory potency of the gases increased in the order ethylene < propylene < 1-butene. Additionally, scanning electron microscopy showed that cells treated with unsaturated hydrocarbon gases were damaged, including invagination of the cell surface.

Toxicity of ethylene combustion condensates is directly proportional to their carbon content.

Numerous epidemiological studies have shown a strong link between air pollution and human morbidity and mortality. Combustion sources are most significant contributors to the urban air pollution. So far, toxicological research has focused predominantly on combustion generated particulate matter, thereby neglecting chemical complexity of combustion exhausts. The aim of this study was to assess toxic potential of ethylene combustion condensates, containing both particulate and gaseous combustion by-products, by means of a recombinant bacterial assay called the SWITCH (Salmonella Weighting of Induced Toxicity (Genotoxicity) and Cytotoxicity for Human Health) test. Thereby, the suitability of total organic carbon (TOC) as a parameter for toxicity assessment was also investigated. Ethylene was combusted in a low-pressure burner under controlled laboratory conditions by only varying the carbon/oxygen ratio (C/O=0.63-0.93). Ethylene combustion condensates were generated by drawing 10 l of combustion exhaust at constant flow rate (0.4 l/min) and collecting it in condensated form in glass bottles cooled by liquid nitrogen. Genotoxic and cytotoxic potency of combustion condensates was analyzed with the SWITCH test, based on sequential measurements of luminescence, absorbance and fluorescence outputs of treated bacterial cultures. Our results show correlation between TOC content of combustion condensates and their genotoxicity/cytotoxicity. Moreover, combustion condensates of same TOC concentration exert the same toxic effect regardless of the used C/O ratios during their generation. Our results revealed that toxicologically relevant component(s) of the ethylene combustion exhausts is/are being produced during highly, mildly and non-sooting combustion conditions, only in different proportions. Thereby, total organic carbon proved to be a suitable parameter for the assessment of the toxicity of combustion condensates.

Relationship between GST Yp induction and hepatocyte proliferation in rats treated with phase II drug metabolizing enzyme inducers.

Butylated hydroxyanisole (BHA) and 1,2-bis(2-pyridyl)ethylene (2PY-e) are phase II drug metabolizing enzyme inducers which cause hepatomegaly without hepatocyte hypertrophy and induce glutathione S-transferase Yp (GST Yp, pi-class GST), which is known as a tumor marker. To evaluate the relationship between GST Yp induction and hepatocyte proliferation, male F344/DuCrj rats were treated with BHA, 2PY-e, or phenobarbital (PB) for three or seven days. All three chemicals caused increases in liver weight after three and seven days. Immunohistochemical examinations revealed that BHA and 2PY-e induced GST Yp in the hepatocytes of the periportal and centrilobular areas at three and seven days, respectively, whereas PB did not. Significant increases in the BrdU labeling indices were found in the livers of rats in each of the three-day treatment groups, but the labeling index of rat livers treated with BHA was decreased to the control level at seven days, although the high labeling indices of 2PY-e and PB persisted at seven days. Double immunostaining confirmed that BrdU-positive nuclei corresponded to GST Yp-positive hepatocytes in both BHA and 2PY-e treated rats. These results suggest that the GST Yp induction caused by BHA or 2PY-e has some kind of relationship with hepatocyte proliferation.

Identification of polypeptides expressed in response to vinyl chloride, ethene, and epoxyethane in Nocardioides sp. strain JS614 by using peptide mass fingerprinting.

Enzymes expressed in response to vinyl chloride, ethene, and epoxyethane by Nocardioides sp. strain JS614 were identified by using a peptide mass fingerprinting (PMF) approach. PMF provided insight concerning vinyl chloride biodegradation in strain JS614 and extends the use of matrix-assisted laser desorption-ionization time of flight mass spectrometry as a tool to enhance characterization of biodegradation pathways.

A screening test for the determination of ethylene sensitivity.

Ethephon, which releases ethylene within plant tissues after application, was chosen to perform assessments of the relative sensitivity of crops to ethylene and to determine which stages of plant development were most sensitive. The species chosen were: barley, wheat, oats, canola and field pea, all of which are important crops in the province of Alberta, Canada. Plants were treated with ethephon at one of 7 different stages. Plants were assessed for their vegetative and reproductive growth, including height, biomass, yield and seed quality. Visual symptoms were photographed and documented to compare them with symptoms caused by ethylene applied as a gas. It was concluded that in barley, wheat and canola the late vegetative and early reproductive stages were most sensitive, at least when sensitivity was defined as reductions in yield and quality. As for field pea, ethephon had no effect on yield but did cause increased numbers of pods, which in certain conditions could lead to increased yields. Significant effects on vegetative growth were only observed in the early vegetative stages of development but with no effects on yield. The screening protocol successfully identified sensitive cultivars and growth stages for further investigation of the effects of ethylene exposure.

Proteome analysis of gametophores identified a metallothionein involved in various abiotic stress responses in Physcomitrella patens.

Physcomitrella patens is a model plant for studying gene function using a knockout strategy. To establish a proteome database for P. patens, we resolved over 1,500 soluble proteins from gametophore and protonema tissues by two-dimensional electrophoresis (2-DE) and obtained peptide mass fingerprints (PMFs) by matrix-assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF-MS). Using expressed sequence tags (ESTs), we were able to predict the identities of 90 protein spots. Most of these were related to energy or primary metabolism. Comparative proteome analysis was used to identify proteins specific for each of the tissue types. One of these was a metallothionein type-2 (PpMT2) protein that was highly upregulated in gametophore tissue. PpMT2 was induced in both the gametophore and protonema following culture on solid media and in response to various abiotic stresses such as copper, cadmium, cold, indole-3-acetic acid, and ethylene. We suggest that PpMT2 is not only involved in metal binding and detoxification, but also in many biological aspects as a metal messenger or a protein with additional functions.