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PubMed2003

A validated method for rapid analysis of ethane in breath and its application in kinetic studies in human volunteers.

Oxidative stress may initiate lipid peroxidation that generates ethane. Ethane, at low concentrations, is eliminated by pulmonary exhalation. Previous methods have not allowed frequent sampling, thus ethane kinetics has not been studied in man. A validated method over the range 3.8-100,000 ppb with a limit of quantitation of 3.8 ppb (CV 9.3%) based on cryofocusing technique of a 60 ml breath sample allowed frequent sampling. Due to a rapid analytical procedure batches of more than 100 samples may be analyzed. In human volunteers (24-55 years) uptake was studied for up to 23 min (n = 9), elimination was studied for 210 min (n = 9). Ethane was inhaled (concentrations varied from 16 to 29 ppm (parts per million)) through a non-rebreathing system; sampling was performed with short intervals from the expiratory limb. Samples were also drawn from the inhalatory limb. Ninety-five percent of steady state (inspired) concentration was reached within 1.75 min. Five percent of the initially inhaled concentrations was found in exhaled air 1.5 min after termination of inhalation. A terminal mean half life of 31 min for ethane was also observed. The data indicate that frequent sampling will be necessary to capture relevant changes in breath ethane.

Adult↗
PubMed1995

Effect of oxygen concentration on production of ethane and thiobarbituric acid-reactive substances by peroxidizing lung and liver homogenates and formation of ethanol by peroxidizing docosahexaenoic acid preparations under hyperoxic conditions.

The oxygen dependence of ethane formation was investigated in rat lung and liver homogenates, incubated in sealed flasks, in which the peroxidation was stimulated by the addition of ferrous ions. For both tissues, the production of ethane was maximal under a 20% oxygenated gas phase, while hyperoxic conditions led to a decreased ethane in the gas phase. The formation of thiobarbituric acid-reactive substances (TBA-RS), another marker of the lipid peroxidation process, in the homogenates of lung and liver was strongly stimulated at 100% compared to 20% oxygen. Experiments were also carried out on iron-stimulated peroxidation of pure docosahexaenoic acid preparations, which under air led to a large production of ethane. As for tissue homogenates, the TBA-RS content was increased in the presence of 100% oxygen. Those conditions, however, did not induce an increase in ethane production but led to the formation of ethanol. Therefore, the quenching of ethyl radical by molecular oxygen seems to be a very attractive hypothesis to explain the lack of increased ethane production in favor of ethanol when iron-induced lipid peroxidation was stimulated by oxygen.

Animals↗
PubMed1989

Ethane production rates and minute ventilation.

Ethane quantitated in the expired alveolar gas is a noninvasive measure of free radical activity. This method has been criticized for lack of control of minute ventilation (VE) in spontaneously breathing animals, although ethane, which is poorly soluble in tissues, should not be affected by changes in VE. We measured ethane elimination rates in six strain 13 guinea pigs (GP13) during spontaneous room air breathing and in six room air breathing, pentobarbital-anesthetized, tracheostomized, externally warmed, mechanically ventilated GP13s at various levels of VE. In the ventilated animals, weight0.75/VE (metabolic activity corrected for VE) was a linear function of arterial CO2 tension (PaCO2) drawn from arterial line (r = 0.72, P less than 0.005). However, weight0.75/VE did not correlate with ethane elimination rates (r = 0.12, not significant). The mean (+/- SD) ethane elimination rates in the spontaneously breathing animals was 3.15 +/- 0.96 pmol.min-1.100 g-1 and was not significantly different from the mean rate in the mechanically ventilated animals (3.11 +/- 1.37) over a range of VE's. These data demonstrate that ethane elimination rates are not affected by changes in VE and are unaffected by pentobarbital anesthesia.

Animals↗
PubMed1999

Breath ethane as a marker of reactive oxygen species during manipulation of diet and oxygen tension in rats.

Breath ethane, O2 consumption, and CO2 production were analyzed in 24-mo-old female Fischer 344 rats that had been fed continuously ad libitum (AL) or restricted 30% of AL level (DR) diets since 6 wk of age. Rats were placed in a glass chamber that was first flushed with air, then with a gas mixture containing 12% O2. After equilibration, a sample of the outflow was collected in gas sampling bags for subsequent analyses of ethane and CO2. The O2 and CO2 levels were also directly monitored in the outflow of the chamber. O2 consumption and CO2 production increased for DR rats. Hypoxia decreased O2 consumption and CO2 production for the AL-fed and DR rats. These changes reflect changes in metabolic rate due to diet and PO2. A significant decrease in ethane generation was found in DR rats compared with AL-fed rats. Under normoxic conditions, breath ethane decreased from 2.20 to 1.61 pmol ethane/ml CO2. During hypoxia the levels of ethane generation increased, resulting in a DR-associated decrease in ethane from 2.60 to 1.90 pmol ethane/ml CO2. These results support the hypothesis that DR reduces the level of oxidative stress.

Aging↗
PubMed2000

Exhaled ethane is elevated in cystic fibrosis and correlates with carbon monoxide levels and airway obstruction.

Ethane is produced from lipid peroxidation and can be measured in the exhaled air. Cystic fibrosis (CF) is characterized by recurrent respiratory infections, release of reactive oxygen species by inflammatory cells, and increased oxidative stress. We measured exhaled ethane in 23 CF subjects (mean age +/- SEM, 21 +/- 4 yr; 10 male, FEV(1) 62 +/- 4%) and compared it with two other noninvasive markers of oxidative stress and inflammation, carbon monoxide (CO) and nitric oxide (NO). Exhaled ethane was collected during a flow and pressure-controlled exhalation into a reservoir discarding dead space air contaminated with ambient air. A sample (2 ml) of the expired air was analyzed by chromatography. Ethane levels were elevated in patients not on steroids (n = 13, 1.99 +/- 0.20 ppb) compared with steroid-treated patients (n = 10, 0.67 +/- 0.09 ppb, p < 0.01) and with 14 nonsmoking control (8 men, age 33 +/- 2.8 yr) subjects (0.82 +/- 0.40 ppb, p < 0.05). In patients not on steroid treatment ethane was correlated to airway obstruction as assessed by the ratio of residual volume to total lung capacity (RV/ TLC) (r = 0. 66, p < 0.05) and exhaled CO (r = 0.65, p < 0.05). CO concentrations were also higher in patients not on steroid treatment (3.4 +/- 0.2 ppm) than in steroid-treated patients (2.6 +/- 0.1 ppm, p < 0.05), whereas NO concentrations were not influenced by steroid treatment (3.0 +/- 0.4 ppm and 2.9 +/- 0.2 ppm, p > 0.05) and were lower than in a control group (7.0 +/- 0.4 ppb, p < 0.05). Exhaled ethane is elevated in CF, reduced in steroid-treated patients and correlates with CO and RV/TLC; therefore, it may be a useful noninvasive marker of oxidative stress.

Adult↗
PubMed1988

Ethane production rate in rats exposed to high oxygen concentration.

Production rates for ethane gas, a hydrocarbon byproduct of lipid peroxidation, measured from the ethane present in the exhaled breath of rats, were used to determine changes in oxygen-free radical activity. Rates of ethane production were measured in rats housed in metabolic chambers and exposed to room air and to high oxygen concentrations. Expired ethane, adsorbed onto activated charcoal and then liberated by heating, was measured by gas chromatography. Ethane production rates in groups of 8 rats increased during 8 h of 100% oxygen exposure from a mean (+/- SE) room air value of 11.30 +/- 1.15 to 27.85 +/- 2.93 pmol/min/100 g rat (p less than 0.005). The mean (+/- SE) percent increases in ethane production after exposure to 100% oxygen in 8 rats pretreated with 0.1 mg/100 g of vitamin E in corn oil vehicle (0.1 ml/100 g) injected intraperitoneally and in a group of 5 rats injected with vehicle alone averaged 157.16 +/- 37.83% and 150.98 +/- 25.19%, respectively. The percent changes noted were not significantly different as measured by analysis of variance. These data indicate that lipid peroxidative activity, hence oxygen-free radical activity, increases in normally fed rats exposed to hyperoxia at a time prior to the previously reported neutrophil influx into the lungs of similarly exposed rats and that it is not attenuated by pretreatment with vitamin E.

Analysis of Variance↗
PubMed1987

Elevated lipid peroxidation in rats induced by dietary lipids and N-nitrosodimethylamine and its inhibition by indomethacin monitored via ethane exhalation.

The effect of dietary lipids alone or in combination with an administered carcinogen, N-nitrosodimethylamine (NDMA), on whole body lipid peroxidation was studied in rats in vivo. Groups of rats were fed diets containing 2%, 12.5%, or 25% of either saturated or polyunsaturated fat. Lipid peroxidation in individual animals was determined by measuring the concentration of ethane in exhaled air. Increased ethane exhalation was found in rats when the amount of dietary fat was increased from 2% to 12.5%, but animals receiving 12.5% or 25% fat in the diet exhaled ethane at similar rates. Rats consuming polyunsaturated fat exhaled more ethane than those eating saturated fat. In all groups, NDMA administration drastically increased ethane exhalation. Indomethacin completely blocked the increase in ethane exhalation caused by dietary lipids.

Animals↗
PubMed1996

Exhaled ethane and antioxidant vitamin supplements in active smokers.

To determine the effect of nutritional agents on lipid peroxidation, 10 smokers were given 6 mg beta carotene, 200 IU vitamin E, and 250 mg vitamin C 4 times daily for 3 weeks. Lipid peroxidation was assessed by measuring baseline and postsupplementation levels of exhaled ethane. There was a 29% decrease in mean (+/-SD) exhaled ethane (4.06 +/- 1.49 vs 2.90 +/- 1.29 pmol.kg-1.min-1), with individual levels decreasing in 8 of the 10 smokers (p < 0.05, Wilcoxon sign rank test). Three nonsmokers had very low baseline levels of ethane that did not change with supplementation. Ethane production correlated with active (packs per day) and lifelong (pack-years) tobacco consumption. Also, a strong correlation was found between the decline in ethane output after micronutrient supplementation and the presupplement FEV1. Therefore, antioxidant vitamin supplementation resulted in attenuation of smoking-related lipid peroxidation, and the decreases in ethane production appears to be associated with preserved lung function.

Antioxidants↗
PubMed1991

Heightened susceptibility of fish oil polyunsaturate-enriched neoplastic cells to ethane generation during lipid peroxidation.

We have studied the generation of volatile hydrocarbons by fatty acid-modified L1210 leukemia cells in tissue culture as a measure of lipid peroxidation. There was considerable generation of ethane, and this was dependent on cell number and Fe2+ concentration; it was eliminated by antioxidants and augmented by ascorbic acid. The assay was sensitive and reproducible; ethane was detected when as little as 0.03% of the cellular n-3 (omega-3) fatty acids were peroxidized. To gain further understanding we used a lipid modification model that allows study of cells enriched with fatty acids of different degrees of unsaturation. The quantity of ethane generated was greatest by cells modified with fatty acids of the n-3 family, and there was a high direct correlation of percentage of n-3 fatty acids contained in cellular lipids with peroxidation as measured by ethane generation. Ethane generation was more sensitive in detecting peroxidation than loss of polyunsaturated fatty acids. We conclude that lipid-supplemented leukemic cells produce ethane, and that the rate of generation is a sensitive, quantitative, and highly useful measure of lipid peroxidation when small amounts of iron are present.

Animals↗
PubMed1994

[Expired ethane as a non-invasive marker of the course of experimental multiple organ dysfunction syndrome (MODS)].

UNLABELLED: BACKGROUND AND WORK HYPOTHESIS: The mechanisms of organ damage in MODS are unclear. Given that lipid peroxidation induced by oxygen radicals may play a key role in organ damage, expired ethane, a marker of lipid peroxidation, could be correlated to the entity and evolution of experimental MODS. STUDY DESIGN AND METHODS: Forty wistar male rats (250 +/- 15 g body weight) were intraperitoneally injected with 10 ml of Zymosan mineral oil suspension (2.5%) to provoke MODS. Survival and symptoms were noted daily. On the 2nd, 7th and 14th day the animals underwent thorax CT scanning. CT images were processed to evaluate the relative density of lung parenchima. Expired ethane was measured using mass spectrometer and percentual changes were noted. Relative organ weight (liver and lung) were measured in 2nd, 7th and 14th day. STATISTICAL ANALYSIS: Pearson's linear correlation. RESULTS: The results show that maximal lung damage took place at the same moments as ethane concentrations peaked. A strict correlation (r = 0.93; p < 0.0001) was found between lung density and expired ethane. Strict correlation was found between organ weight, symptoms, survival and ethane production. CONCLUSIONS: Lipid peroxidation, as expressed by ethane production, might be an important cause of organ damage in MODS.

Animals↗
PubMed2004

Crossed beams and theoretical studies of the dynamics of hyperthermal collisions between Ar and ethane.

Crossed molecular beams experiments and classical trajectory calculations have been used to study the dynamics of Ar+ethane collisions at hyperthermal collision energies. Experimental time-of-flight and angular distributions of ethane molecules that scatter into the backward hemisphere (with respect to their original direction in the center-of-mass frame) have been collected. Translational energy distributions, derived from the time-of-flight distributions, reveal that a substantial fraction of the collisions transfer abnormally large amounts of energy to internal excitation of ethane. The flux of the scattered ethane molecules increased only slightly from directly backward scattering to sideways scattering. Theoretical calculations show angular and translational energy distributions which are in reasonable agreement with the experimental results. These calculations have been used to examine the microscopic mechanism for large energy transfer collisions ("supercollisions"). Collinear ("head-on") or perpendicular ("side-on") approaches of Ar to the C-C axis of ethane do not promote energy transfer as much as bent approaches, and collisions in which the H atom is "sandwiched" in a bent Ar...H-C configuration lead to the largest energy transfer. The sensitivity of collisional energy transfer to the intramolecular potential energy of ethane has also been examined.

Journal Article↗
PubMed1979

Ethylene and Ethane Production from Sulfur Dioxide-injured Plants.

After alfalfa (Medicago sativa) seedlings were exposed to approximately 0.7 microliter per liter SO(2) for 8 hours, elevated ethylene and ethane production was observed. Ethylene production peaked about 6 hours and returned to control levels by about 24 hours following the fumigation, while ethane production peaked about 36 hours and was still above control levels 48 hours after the fumigation. Light had an opposite effect upon the production of the two gases: ethane production rates were higher from plants held in light, whereas ethylene production rates were higher from those held in the dark. Peak ethylene and ethane production rates from SO(2)-treated plants were about 10 and 4 to 5 times greater, respectively, than those of the control plants. Ethylene appeared to be formed primarily from stressed yet viable leaves and ethane from visibly damaged leaves. The different time courses and light requirements for ethylene and ethane production suggest that these two gases were formed via different mechanisms. Light appears to have a dual role. It enhances SO(2)-induced cellular damage and plays a role for repairs.

Journal Article↗
PubMed2004

Effects of ethane-1-hydroxy-1,1-diphosphonate on ossification of the posterior longitudinal ligament in Zucker fatty rats.

PURPOSE: Using Zucker fatty rats as an animal model, we evaluate the effectiveness of ethane-1-hydroxy-1,1-diphosphonate on ossification of the posterior longitudinal ligament by histopathologically investigating the prodromal, early, and advanced stages of ossification of the spinal ligaments. METHODS: 73 Zucker fatty rats were allocated to the ethane-1-hydroxy-1,1-diphosphonate group (n=33) and the control group (n=40). The former group was fed ethane-1-hydroxy-1,1-diphosphonate daily. The feed was given starting 2 months after birth and continued until the rats were killed at 3 to 18 months later. Chemical analysis of the blood, radiographic tests, and histopathological examination were then conducted for both groups. RESULTS: The results showed that ossification of the spinal ligaments involved excessive cartilage cell proliferation around areas affected by enthesitis; enlargement of the fibrocartilage tissue layer; ligament thickening; calcification of the matrix around the cartilage cells; and ossification of the spinal ligaments through enchondral ossification. Radiographic examinations showed that osteoproliferation in vertebral bodies in rats receiving ethane-1-hydroxy-1,1-diphosphonate was generally suppressed compared with controls, whereas histopathological examinations found no clear difference in cartilage cell proliferation in areas affected by enthesitis between the two groups, indicating the absence of calcification or osteo-proliferation in areas affected by enthesitis for the rats receiving ethane-1-hydroxy-1,1-diphosphonate. CONCLUSION: Ethane-1-hydroxy-1,1-diphosphonate is effective in suppressing progressive ligament ossification.

Animals↗
PubMed1992

Breath ethane: a specific indicator of free-radical-mediated lipid peroxidation following reperfusion of the ischemic liver.

A major component of the organ injury mediated by toxic oxidants, such as seen following reperfusion of the ischemic liver, is due to the peroxidation of polyunsaturated fatty acids, especially of cell membranes. We utilized the measurement of exhaled breath ethane, a metabolic product unique to oxidant-mediated lipid peroxidation, as a noninvasive indicator of this process in swine liver subjected to warm ischemia/reperfusion. Under rigorously controlled anesthesia conditions, pig livers were subjected to 2 h of warm total ischemia, followed by reperfusion in situ. Expired air was collected and its ethane content quantitated by a novel gas chromatographic technique. The time course of breath ethane generation correlated closely with the appearance of hepatocellular injury as measured by impairment of Factor VII generation and other measures of liver integrity. Moreover, the administration of the specific superoxide free radical scavenger, superoxide dismutase (SOD), significantly attenuated both the elaboration of ethane and the hepatocellular injury. These findings not only provide confirmation of the previously reported link between hepatocellular injury by free radicals generated at reperfusion, but also establish the use of expired breath ethane analysis as a sensitive, specific, and noninvasive indicator of the injury process in real time.

Alanine Transaminase↗
PubMed2005

Effect of maximal dynamic exercise on exhaled ethane and carbon monoxide levels in human, equine, and canine athletes.

Exercise-induced oxidative stress (EIOS) refers to a condition where the balance of free radical production and antioxidant systems is disturbed during exercise in favour of pro-oxidant free radicals. Breath ethane is a product of free radical-mediated oxidation of cell membrane lipids and is considered to be a reliable marker of oxidative stress. The heatshock protein, haem oxygenase, is induced by oxidative stress and degrades haemoglobin to bilirubin, with concurrent production of carbon monoxide (CO). The aim of this study was to investigate the effect of maximal exercise on exhaled ethane and CO in human, canine, and equine athletes. Human athletes (n = 8) performed a maximal exercise test on a treadmill, and canine (n = 12) and equine (n = 11) athletes exercised at gallop on a sand racetrack. Breath samples were taken at regular intervals during exercise in the human athletes, and immediately before and after exercise in the canine and equine athletes. Breath samples were stored in gas-impermeable bags for analysis of ethane by laser spectroscopy, and CO was measured directly using an electrochemical CO monitor. Maximal exercise was associated with significant increases in exhaled ethane in the human, equine, and canine athletes. Decreased concentrations of exhaled CO were detected after maximal exercise in the human athletes, but CO was rarely detectable in the canine and equine athletes. The ethane breath test allows non-invasive and real-time detection of oxidative stress, and this method will facilitate further investigation of the processes mediating EIOS in human and animal athletes.

Adult↗
PubMed2005

Reduction of chlorinated ethanes by nanosized zero-valent iron: kinetics, pathways, and effects of reaction conditions.

Nanosized iron (< 100 nm in diameter) was synthesized in the laboratory and applied to the reduction of eight chlorinated ethanes (hexachloroethane (HCA), pentachloroethane (PCA), 1,1,2,2-tetrachloroethane (1,1,2,2-TeCA), 1,1,1,2-tetrachloroethane (1,1,1,2-TeCA), 1,1,2-trichloroethane (1,1,2-TCA), 1,1,1-trichloroethane (1,1,1-TCA), 1,2-dichloroethane (1,2-DCA), and 1,1-dichloroethane (1,1-DCA)) in batch reactors. Reduction of 1,1,1-TCA increased linearly with increasing iron loading between 0.01 and 0.05 g per 124 mL solution (0.08-0.4 g/L). Varying initial concentrations of PCA between 0.025 and 0.125 mM resulted in relatively constant pseudo-first-order rate constants, indicating PCA removal conforms to pseudo-first-order kinetics. The reduction of 1,1,2,2-TeCA decreased with increasing pH; however, dehydrohalogenation of 1,1,2,2-TeCA became important at high pH. All chlorinated ethanes except 1,2-DCA were transformed to less chlorinated ethanes or ethenes. The surface-area-normalized rate constants from first-order kinetics analysis ranged from < 4 x 10(-6) to 0.80 L m(-2) h(-1). In general, the reactivity increased with increasing chlorination. Among tri- and tetrasubstituted compounds, the reactivity was higher for compounds with chlorine atoms more localized on a single carbon (e.g., 1,1,1-TCA > 1,1,2-TCA). Reductive beta-elimination was the major pathway for the chlorinated ethanes possessing alpha,beta-pairs of chlorine atoms to form chlorinated ethenes, which subsequently reacted with nanosized iron. Reductive alpha-elimination and hydrogenolysis were concurrent pathways for compounds possessing chlorine substitution on one carbon only, forming less chlorinated ethanes.

Chlorine Compounds↗
PubMed2004

Effects of potential models on the adsorption of ethane and ethylene on graphitized thermal carbon black. Study of two-dimensional critical temperature and isosteric heat versus loading.

Adsorption of ethylene and ethane on graphitized thermal carbon black and in slit pores whose walls are composed of graphene layers is studied in detail to investigate the packing efficiency, the two-dimensional critical temperature, and the variation of the isosteric heat of adsorption with loading and temperature. Here we used a Monte Carlo simulation method with a grand canonical Monte Carlo ensemble. A number of two-center Lennard-Jones (LJ) potential models are investigated to study the impact of the choice of potential models in the description of adsorption behavior. We chose two 2C-LJ potential models in our investigation of the (i) UA-TraPPE-LJ model of Martin and Siepmann for ethane and Wick et al. for ethylene and (ii) AUA4-LJ model of Ungerer et al. for ethane and Bourasseau et al. for ethylene. These models are used to study the adsorption of ethane and ethylene on graphitized thermal carbon black. It is found that the solid-fluid binary interaction parameter is a function of adsorbate and temperature, and the adsorption isotherms and heat of adsorption are well described by both the UA-TraPPE and AUA models, although the UA-TraPPE model performs slightly better. However, the local distributions predicted by these two models are slightly different. These two models are used to explore the two-dimensional condensation for the graphitized thermal carbon black, and these values are 110 K for ethylene and 120 K for ethane.

Adsorption↗
PubMed2005

On two alternative mechanisms of ethane activation over ZSM-5 zeolite modified by Zn2+ and Ga1+ cations.

The activation of ethane over zinc- and gallium-modified HZSM-5 dehydrogenation catalysts was studied by diffuse reflectance infrared spectroscopy. Hydrocarbon activation on HZSM-5 modified by bivalent Zn and univalent Ga cations proceeds via two distinctly different mechanisms. The stronger molecular adsorption of ethane by the acid-base pairs formed by distantly separated cationic Zn2+ and basic oxygen sites results already at room temperature in strong polarizability of adsorbed ethane and subsequent heterolytic dissociative adsorption at moderate temperatures. In contrast, molecular adsorption of ethane on Ga+ cations is weak. At high temperatures dissociative hydrocarbon adsorption takes place, resulting in the formation of ethyl and hydride fragments coordinating to the cationic gallium species. Whereas in the zinc case a Brønsted acid proton is formed upon ethane dissociation, decomposition of the ethyl fragment on gallium results in gallium dihydride species and does not lead to Brønsted acid protons. This difference in alkane activation has direct consequences for hydrocarbon conversions involving dehydrogenation.

Adsorption↗