Eugenol causes oxidant-mediated edema in isolated perfused rabbit lungs

Cytotoxicity, Differentiation, and Biocompatibility of Root-End Filling: A Comprehensive Study

Assessing the biocompatibility of endodontic root-end filling materials through cell line responses is both essential and of utmost importance. This study aimed to the cytotoxicity of the type of cell death through apoptosis and autophagy, and odontoblast cell-like differentiation effects of MTA, zinc oxide-eugenol, and two experimental Portland cements modified with bismuth (Portland Bi) and barium (Portland Ba) on primary cell cultures. Material and methods: The cells corresponded to human periodontal ligament and gingival fibroblasts (HPLF, HGF), human pulp cells (HPC), and human squamous carcinoma cells from three different patients (HSC-2, -3, -4). The cements were inoculcated in different concentrations for cytotoxicity evaluation, DNA fragmentation in electrophoresis, apoptosis caspase activation, and autophagy antigen reaction, odontoblast-like cells were differentiated and tested for mineral deposition. The data were subject to a non-parametric test. Results: All cements caused a dose-dependent reduction in cell viability. Contact with zinc oxide-eugenol induced neither DNA fragmentation nor apoptotic caspase-3 activation and autophagy inhibitors (3-methyladenine, bafilomycin). Portland Bi accelerated significantly (p < 0.05) the differentiation of odontoblast-like cells. Within the limitation of this study, it was concluded that Portland cement with bismuth exhibits cytocompatibility and promotes odontoblast-like cell differentiation. This research contributes valuable insights into biocompatibility, suggesting its potential use in endodontic repair and biomimetic remineralization.

New Analytical Method for Quantifying Flavoring Chemicals of Potential Respiratory Health Risk Concerns in e-Cigarette Liquids

Numerous flavoring chemicals are added to e-cigarette liquids to create various flavors. Flavorings provide sensory experience to users and increase product appeal; however, concerns have been raised about their potential inhalation toxicity. Estimating potential health risk of inhaling these chemicals has been challenging since little is known about their actual concentrations in e-cigarette products. To date, a limited number of analytical methods exist to measure the concentrations of flavoring chemicals in e-cigarette products. We have developed an analytical method that accurately and precisely measures the concentrations of 20 flavoring chemicals of potential inhalation risk concerns: 2,3,5-trimethylpyrazine, acetoin, benzaldehyde, benzyl alcohol, butanoic acid, dl-limonene, ethyl maltol, ethyl salicylate, ethyl vanillin, eucalyptol, eugenol, furaneol, isovanillin, l-menthol, maltol, methyl salicylate, pulegone, trans-cinnamaldehyde, triacetin, and vanillin. Calibration and QC solutions were prepared in 50:50 propylene glycol (PG):vegetable glycerin (VG) and 5% H₂O and flavoring concentrations ranging from 0.02 to 10.00 mg/ml. Samples of commercial e-cigarette liquids, calibration and QC solutions were combined with 30 µL of an internal standard mix (benzene-d6, pyridine-d5, chlorobenzene-d5, naphthalene-d8 and acenaphthene-d10; 1 mg/ml each) and were diluted 100-fold into methanol. Analysis was performed on an Agilent 7890B/7250 GC/Q-TOF using a DB-624UI column (30 m x 0.25 mmID x 1.4 μm film thickness), with a total runtime of 13.5 min. Calibration curves were fit using a weighted quadratic model and correlations of determination (r²) values exceeded 0.990 for all chemicals. Bias and precision tests yielded values less than 20% and lower limits of quantitation (LLOQ) ranged from 0.02 to 0.63 mg/ml. Over 200 commercially available products, purchased or collected from adult e-cigarette users and spanning a range of flavor categories, were evaluated with this method. Concentrations of pulegone, a suspected carcinogen, varied from below limit of quantitation (BLOQ) to 0.32 mg/ml, while acetoin and vanillin, known precursors to more cytotoxic byproducts, ranged from BLOQ to 1.52 mg/ml and from BLOQ to 16.22 mg/ml, respectively. This method features a wide dynamic working range and allows for a rapid routine analysis of flavoring additives in commercial e-cigarette liquids.

Simultaneous Determination of Coumarin and Its Derivatives in Tobacco Products by Liquid Chromatography-Tandem Mass Spectrometry

In this paper an analytical method based on high performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS) for the determination of coumarin and its derivatives in tobacco products was developed. The MS/MS fragmentation pathways of the eight coumarins were elucidated. The new analytical method was defined based on two main axes, an extraction procedure with acetonitrile and analyte detection performed by HPLC-MS/MS in electron impact mode. The excellent selectivity and sensitivity achieved in multiple reaction monitoring (MRM) mode allowed satisfactory confirmation and quantitation for the coumarin flavor additives. Under the optimized gradient elution conditions, it took only 4.5 min to separate all eight coumarins. Good linearity for all the analytes were confirmed by the correlation coefficient r², ranging from 0.9987 to 0.9996. The limits of detection (LODs) and limits of quantitation (LOQs) of these compounds were in the range of 0.5-1.7 μg/kg and 1.7-5.2 μg/kg, respectively. The average recoveries at three spiked levels (LOQ, 1.5LOQ, 2LOQ) were all in the range of 69.6%-95.1% with RSDs (n = 6) lower than 5.3%. The method of HPLC-MS/MS developed in this study was initially applied to the research of coumarin flavor additives in tobacco products collected from the located market in Beijing from China and proved to be accurate, sensitive, convenient and practical.

Efficacy and mechanisms of behavioral therapy components for insomnia coexisting with chronic obstructive pulmonary disease: study protocol for a randomized controlled trial

BACKGROUND

Difficulty falling asleep, staying asleep or poor-quality sleep (insomnia) is common in people with chronic obstructive pulmonary disease (COPD). Insomnia is related to greater mortality and morbidity, with four times the risk of mortality for sleep times below 300 min. However, insomnia medications are used with caution in COPD due to their potential adverse effects. While cognitive behavioral therapy for insomnia (CBT-I) is effective for people with primary insomnia and people with other chronic illnesses, the efficacy and mechanisms of action of such a therapy are yet unclear in people with both insomnia and COPD. The purpose of this study is to rigorously test the efficacy of two components of insomnia therapy - CBT-I and COPD education (COPD-ED) - in people with coexisting insomnia and COPD, and to identify mechanisms responsible for therapy outcomes. The rationale for the proposed study is that once the efficacy and mechanisms of CBT-I and COPD-ED are known, new and innovative approaches for insomnia coexisting with COPD can be developed to non-pharmacologically minimize insomnia and fatigue, thereby leading to longer, higher-quality and more productive lives for people with COPD, and reduced societal cost due to the effects of insomnia.

METHODS

We are conducting a randomized, controlled, parallel-group (N = 35 each group) comparison of CBT-I, COPD-ED and non-COPD, non-sleep health education Attention Control (AC) using a highly efficient four-group design. Arm 1 comprises 6 weekly sessions of CBT-I + AC; Arm 2 = 6 weekly sessions of COPD-ED + AC; Arm 3 = 6 weekly sessions of CBT-I + COPD-ED; and Arm 4 = 6 weekly sessions of AC. This design will allow completion of the following specific aims: (1) to determine the efficacy of individual treatment components, CBT-I and COPD-ED, on insomnia and fatigue, (2) to define the mechanistic contributors to the outcomes after CBT-I and COPD-ED.

DISCUSSION

The research is innovative because it represents a new and substantive departure from the usual insomnia therapy, namely by testing traditional CBT-I with education to enhance outcomes. The work proposed in aims 1 and 2 will provide systematic evidence of the efficacy and mechanisms of components of a novel approach to insomnia comorbid with COPD. Such results are highly likely to provide new approaches for preventive and therapeutic interventions for insomnia and fatigue in COPD.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01973647 . Registered on 22 October 2013.

The changing face of tobacco use among United States youth

Tobacco use, primarily in the form of cigarettes, is the leading cause of preventable morbidity and mortality in the United States (U.S.). The adverse effects of tobacco use began to be recognized in the 1940's and new hazards of active smoking and secondhand smoke (SHS) exposure from cigarettes continue to be identified to this day. This has led to a sustained and wide-ranging array of highly effective regulatory, public health, and clinical efforts that have been informed by extensive scientific data, resulting in marked decreases in the use of cigarettes. Unfortunately, the dramatic recent decline in cigarette use in the U.S., has been accompanied by an upsurge in adolescent and young adult use of new, non-cigarette tobacco and nicotine-delivery products, commonly referred to as alternative tobacco products (ATPs). Commonly used ATPs include hookah, cigars, smokeless tobacco, and electronic cigarettes. While there have been a number of review articles that focus on adult ATP use, the purpose of this review is to provide an overview of what is, and is not known about emerging ATP use among U.S. adolescents on a national scale; as well as to identify research gaps in knowledge, and discuss future health and policy needs for this growing public health concern. This paper is not meant to systemically review all published survey data, but to present clear depiction of selected ATP usage in youth populations using national survey data.

An unexpected positive hypersensitive reaction to eugenol

Eugenol is an active, principal aromatic liquid responsible for several pharmacological activities. It is widely used in dental practice to relieve pain arising from various sources, such as pulpitis and dentinal hypersensitivity. As a primary irritant and sensitiser, it is known to cause contact urticaria as well as chronic urticaria. However, eugenol causes allergic contact dermatitis, possibly because it can react directly with proteins to form conjugate and reactive haptens. It is found that eugenol in various dental preparations-especially in the case of some zinc oxide-contains preparations such as periodontal dressings and root canal cements. This can cause hypersensitivity when it comes in contact with gingiva or teeth. This article presents a case of immediate allergic contact urticaria to eugenol during dental treatment.

Simultaneous determination of 23 flavor additives in tobacco products using gas chromatography-triple quadrupole mass spectrometry

A method based on gas chromatography coupled to triple quadrupole tandem mass spectrometry (GC-QqQ MS/MS) was developed for the determination of 23 widely used flavor additives in tobacco products in this paper. The MS/MS fragmentation pathway of the cinnamic esters additives was illustrated. The new analytical method was defined based on two main axes, ultrasonic solvent extraction procedure with dichloromethane and analyte detection performed by GC-QqQ MS/MS in electron impact mode. The excellent selectivity and sensitivity achieved in multiple reactions monitoring (MRM) mode allowed satisfactory confirmation and quantitation for the tobacco flavor additives. The linear range of the 23 flavor additives is 0.2-500.0μg/L with good correlation coefficients (r(2)>0.9963). The limits of detection (LODs) and limits of quantitation (LOQs) of these compounds were in the range 0.1-2.0μg/L and 0.4-6.0μg/kg, respectively. The average recoveries at three spiked levels (LOQ, 2LOQ, 4LOQ) were all in the range 62.1-93.8% with RSDs (n=6) lower than 7.8%. The method of GC-QqQ MS/MS developed in this study was initially applied to the research of flavor additives in 12 retail cigarette samples and proved to be accurate, sensitive, convenient and practical.

The effect of clove and benzocaine versus placebo as topical anesthetics

OBJECTIVES

The purpose of this study was to examine whether the natural herb clove can replace benzocaine as a topical anesthetic.

METHODS

Topical agents were applied to the maxillary canine buccal mucosa of 73 adult volunteers. Four substances were tested in the study: (1) homemade clove gel, (2) benzocaine 20% gel, (3) placebo that resembles clove and (4) a placebo that resembled benzocaine. After 5 min of material application in a randomized, subject-blinded manner, each participant received two needle sticks. Pain response was registered using a 100 mm visual analogue pain scale.

RESULTS

Both clove and benzocaine gels had significantly lower mean pain scores than placebos (p=0.005). No significant difference was observed between clove and benzocaine regarding pain scores.

CONCLUSION

Clove gel might possess a potential to replace benzocaine as a topical agent before needle insertion.

Youth attitudes and beliefs toward alternative tobacco products: cigars, bidis, and kreteks

Youth use of cigars, bidis, and kreteks has spread as youth cigarette use has declined. This study investigates young people's attitudes toward and beliefs about these alternative tobacco products. The study used data from a convenience sample survey of 5,016 7th-through 12th-grade students in Massachusetts. The cigar attitudes receiving the highest endorsement levels were that cigars smell good and are something different to try, whereas the item receiving the lowest endorsement was that cigars give you a goodbuzz. The most endorsed bidi attitudes were that bid is look like joints and are something different to try. For kreteks, the most endorsed items were that kreteks smell good and are something different to try. Multivariate analyses found that reporting that these products tasted, smelled good, or were something different to try predicted use. Because the study was conducted with a convenience sample in one state, results do not necessarily generalize.

Eugenol isolated from the essential oil of Eugenia caryophyllata induces a reactive oxygen species-mediated apoptosis in HL-60 human promyelocytic leukemia cells

Eugenol is a major component of essential oil isolated from the Eugenia caryophyllata (Myrtaceae), which has been widely used as a herbal drug. In this study, we investigated the effects of eugenol on the cytotoxicity, induction of apoptosis, and the putative pathways of its actions in human promyelocytic leukemia cells (HL-60) under the standard laboratory illumination. Eugenol-treated HL-60 cells displayed features of apoptosis including DNA fragmentation and formation of DNA ladders in agarose gel electrophoresis. We observed that eugenol transduced the apoptotic signal via ROS generation, thereby inducing mitochondrial permeability transition (MPT), reducing anti-apoptotic protein bcl-2 level, inducing cytochrome c release to the cytosol, and subsequent apoptotic cell death. Taken together, the present study demonstrated that ROS plays a critical role in eugenol-induced apoptosis in HL-60, and this is the first report on the mechanism of the anticancer effect of eugenol.

Characteristics of users of cigars, bidis, and kreteks and the relationship to cigarette use

BACKGROUND

In the 1990s, youth use of alternative tobacco products including cigars, bidis, and kreteks increased. This article discusses the prevalence of youth use of cigars, bidis, and kreteks, and characteristics of users.

METHODS

The Cigar Use Reasons Evaluation (CURE)-a questionnaire assessing alternative tobacco use and associated attitudes and behaviors-was administered to middle and high school students from 12 school districts across Massachusetts.

RESULTS

Males were more likely to use all forms of alternative tobacco and females more likely to smoke cigarettes. Hispanics were less likely to smoke kreteks or use smokeless tobacco. Urban students were more likely to smoke bidis or use smokeless tobacco than suburban or rural youth. Most smokeless and alternative tobacco users were lifetime cigarette smokers. There was, however, a significant group of cigar smokers, associated with higher parental education, who were not current cigarette smokers.

CONCLUSIONS

Use of alternative tobacco poses a risk to the success of tobacco control efforts. While many alternative tobacco users smoke cigarettes, some alternative tobacco users are current cigarette smokers. Cigar use thus constitutes a potential serious risk for youth who otherwise might not be exposed to tobacco.

Reactive oxygen species generation and photo-cytotoxicity of eugenol in solutions of various pH

In order to clarify the mechanism of photo-damage caused by eugenol (4-allyl-2-methoxyphenol), we measured cell survival in the presence of eugenol at concentrations of 10(-3) - 10(-7) M, with and without VL (visible light) irradiation by a VL dental lamp and at various pHs (7.2, 7.8 and 8.2) using two different cells (HSG, a human submandibular gland tumor cell line; HGF, a human gingival fibroblast in primary culture). Also, ROS (reactive oxygen species) generation in the above adherent single cells was measured by ACAS laser cytometry combined with CDFH-DA, a peroxide probe. The survival of both HSG and HGF cells treated with eugenol was significantly decreased as the VL irradiation time and/or the pH of the medium was increased. The amount of ROS generated from eugenol was also enhanced by increasing the VL irradiation time and elevating the pH of the medium. Cytotoxicity and ROS generation of HGF cells were significantly lower than that of HSG cells. Glutathione (1 mM) or cysteine (1 mM) protected the photo damages. We conclude that the cytotoxicity of VL-irradiated eugenol possibly was caused by the generation of eugenol radicals and additionally by ROS, both of which were produced dependent on the dose of eugenol, length of irradiation time, and pH of the medium.

Solid phase microextraction of alkenylbenzenes and other flavor-related compounds from tobacco for analysis by selected ion monitoring gas chromatography-mass spectrometry

Some constituents found in natural flavorings are known to exhibit toxic properties. We developed a rapid method for quantifying 12 flavor-related compounds in cigarette tobacco using headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry. Using selected ion monitoring, we quantified and positively identified coumarin; pulegone; piperonal and nine alkenylbenzenes, including trans-anethole, safrole, methyleugenol and myristicin in one or more brands of cigarettes. In 62% of 68 brands analyzed, we detected one or more of the flavor-related compounds ranging from 0.0018 to 43 microg/g. Toxic properties of these flavor-related compounds may constitute an additional health risk related to cigarette smoking.

Comparative toxicity of eugenol and its quinone methide metabolite in cultured liver cells using kinetic fluorescence bioassays

Comparative kinetic analyses of the mechanisms of toxicity of the alkylphenol eugenol and its putative toxic metabolite (quinone methide, EQM) were carried out in cultured rat liver cells (Clone 9, ATCC) using a variety of vital fluorescence bioassays with a Meridian Ultima laser cytometer. Parameters monitored included intracellular GSH and calcium levels ([Ca2+]i), mitochondrial and plasma membrane potentials (MMP and PMP), intracellular pH, reactive oxygen species (ROS) generation, and gap junction-mediated intercellular communication (GJIC). Cells were exposed to various concentrations of test compounds (1 to 1000 microM) and all parameters monitored directly after addition at 15 s intervals for at least 10 min. Eugenol depleted intracellular GSH, inhibited GJIC and generation of ROS, and had a modest effect on MMP at concentrations of 10 to 100 microM. At high concentrations (1000 microM), eugenol also affected [Ca2+]i, PMP, and pH. Effects of EQM were seen at lower concentrations (1 to 10 microM). The earliest and most potent effects of either eugenol or EQM were seen on GSH levels and GJIC. Coadministration of glutathione ethyl ester enhanced intracellular GSH levels by almost 100% and completely protected cells from cell death caused by eugenol and EQM. These results suggest that eugenol mediates its hepatotoxic effects primarily through depletion of cytoprotective thiols and interference in thiol-dependent processes such as GJIC. Furthermore, our results support the hypothesis that the toxic effects of eugenol are mediated through its quinone methide metabolite.

In vitro evaluation of the cytotoxicity of pure eugenol

The aim of this study was to assess the cytotoxicity of pure eugenol in an in vitro method by diluting it to various concentrations in alcohol and determining the maximum noncytotoxic concentration. We used solutions of eugenol and ethyl alcohol that are soluble in water in any given proportion. The cytotoxicity of the alcohol itself was determined by using a dose-response curve for concentrations of between 0.017 M and 1.7 M. Various strength concentrations (0.015 to 947 microM) of eugenol in alcohol were prepared; 20 microliters (0.34 M) of ethyl alcohol was added to 1 ml of cell medium. The experiment showed that pure eugenol is toxic for human gingival fibroblasts. Eugenol in an alcohol solution at concentrations of < 1.9 microM is noncytotoxic.

A comparative study of the effects of iloprost and PGE1 on pulmonary arterial pressure and edema formation in the isolated perfused rat lung model

Isolated lungs from male Wistar rats (250-350 g) were perfused at a constant flow rate (10 ml/min, non-recirculating) with Krebs-Ringer-bicarbonate buffer containing 4.5 % bovine serum albumin, and were ventilated at a positive pressure (60 breaths/min). Pulmonary arterial pressure and lung weight (as a measure of edema formation) were recorded continuously. After an equilibration period of 20 minutes the various test compounds were added to the perfusion fluid and experimental recording was continued for another 60 minutes. The effects of the stable PGI2-mimetic, iloprost, of PGE1, and of the biologically active PGE1-metabolite, 13,14-dihydro-PGE1, were evaluated in this model (n = 6). Iloprost showed slight, but not significant vasodilation; however, lung weight remained unchanged. PGE1 and 13, 14-dihydro-PGE1 also caused slight vasodilation, but in contrast to iloprost these compounds induced distinct pulmonary edema. The lung weight gain was discernible at concentrations of 2.8 x 10(-6) mol/l (significant at 2.8 x 10(-5) mol/l; p < or = 0.05) and was accompanied by increases in the wet-weight to dry-weight ratios. These findings were duplicated in a second set of experiments (n = 6) from which the same results were obtained. The results indicate that at high concentrations PGE1 (and 13,14-dihydro-PGE1), but not iloprost, can induce pulmonary edema in rats probably by increasing the permeability of the pulmonary vasculature.

Studies of human airways in vitro: a review of the methodology

The pathophysiology of human airway narrowing is only partly understood. In order to gain more insight in the mechanisms of human lung diseases and potential beneficial therapeutic agents, adequate models are needed. Animal airway models are of limited value since lung diseases such as asthma and chronic obstructive pulmonary disease (COPD) are unique to humans and because the mechanisms of airway narrowing differ between species. Therefore, it is important to perform studies on human isolated airways. We describe the models that have been developed to study airway function in vitro, emphasizing human airway preparations. The easily prepared airway strip and ring preparations are described first. The potential damage during preparation and the interference with airway structure are important drawbacks in these preparations. Lung parenchymal strips, described next, were designed in order to study responsiveness of small airways. However, parenchymal strips are anatomically complex, and responsiveness is determined by the relative amounts of airway and vascular smooth muscle. The lack of reproducibility between species and even within one animal limits their usefulness. Airway tube preparations, in which luminal and serosal stimulation can be separated, enable us to study the modulatory role of the airways epithelium in vitro. Furthermore, airway compliance can be measured. In the isolated perfused lung preparation, relationships between the airways and the vascular system are preserved and the interaction between these two systems can be studied. Weight gain due to fluid extravasation is a problem in this model which has not been used yet to study human lungs in vitro. Next, methodological aspects such as tissue handling and storage, recording of responses, removal of the epithelium, and electrical field stimulation are discussed in some detail. Although animal airways tissue can be studied immediately after removal, human tissue is often obtained with some delay. However, this seems tenable since electron microscopy of lung tissue obtained at autopsy showed that recovery of the preparation occurs during incubation of carbogenated Krebs-Henseleit (K-H) buffer. Dissected airways can be stored overnight in cooled K-H buffer until up to 55 hr after resection without losing viability. Commonly used physiological salt solutions which bath the tissue contain osmotic molecules, ions important for contractility, glucose as a substrate, and a bicarbonate-carbon dioxide buffer.(ABSTRACT TRUNCATED AT 400 WORDS)

Airway constriction by xanthine/xanthine oxidase in guinea pigs in vivo

Reactive oxygens are considered to be one of the mediators involved in inflammation. We investigated the constrictive effects of reactive oxygens generated by aerosolized xanthine/xanthine oxidase (XOD) on the airways of anesthetized guinea pigs. Airway resistance was measured with a modified Konzett-Rössler method and expressed as a change in ventilation overflow (VO). Inhalation of xanthine (1.0 M)/XOD (10, 15 U/ml) caused a significant increase in VO. This airway constriction tended to be enhanced by pretreatment with inhaled superoxide dismutase, but was suppressed by inhaled catalase. Inhalation of hydrogen peroxide caused an airway constriction in a concentration-dependent manner (0.1-2.0 M). Xanthine/XOD significantly enhanced the maximal change in VO after inducing airway inflammation by SO2 exposure. The pretreatment with inhalation of xanthine/XOD did not affect the airway constriction induced by inhaled histamine. However, in SO2-exposed guinea pigs, the inhalation of xanthine/XOD significantly increased the sensitivity to histamine. These results indicate that hydrogen peroxide and other reactive oxygen intermediates produced by xanthine/XOD may cause an airway constriction and airway hyperresponsiveness.

Airway inflammatory effect of hydrogen peroxide in guinea pigs

Reactive oxygens are now considered to be important substances in promoting inflammatory process. Recently, airway inflammation has attracted attention closely linked to bronchial asthma. The present study was undertaken to examine whether hydrogen peroxide, one of the reactive oxygens, could produce airway inflammation. Airway inflammation was assessed by airway vascular permeability in terms of pontamine sky blue (PSB) exudation. Airway resistance was measured with a modified Konzett-Rössler method and was expressed as a change in ventilation overflow. Inhalation of hydrogen peroxide (0.01-1.0 M) markedly caused a PSB exudation in a concentration-dependent manner in all of the trachea, main bronchus, and lungs. The hydrogen peroxide-induced PSB exudation effect was attenuated was attenuated by pretreatment with catalase, although heat-inactivated catalase had no inhibitory effect. Deferoxamine, which inhibits conversion of hydrogen peroxide into hydroxyl radical, decreased the PSB exudation induced by hydrogen peroxide. On the other hand, inhalation of hydrogen peroxide (1.0 M) caused a significant and biphasic increase in ventilation overflow. This airway constriction was suppressed by pretreatment with inhaled catalase, but not by inhaled deferoxamine. These results indicate that hydrogen peroxide causes an intense airway inflammation; this inflammatory effect may be mediated not only by hydrogen peroxide itself but also by hydroxyl radical. Hydrogen peroxide and hydroxyl radical may thus play an important role in bronchial asthma and bronchitis through inducing airway inflammation.

Biological and toxicological consequences of quinone methide formation

Quinone methides are a class of reactive, electrophilic compounds which are capable of alkylating cellular macromolecules. They are formed during xenobiotic biotransformation reactions and are hypothesized to mediate the toxicity of a large number of quinone antitumor drugs as well as several alkylphenols. In addition, oxidation of specific endogenous alkylphenols (e.g. coniferyl alcohol) and alkylcatechols (e.g. N-acetyldopamine, dopa) to quinone methides plays an important role in the synthesis of several complex plant and animal polymers, including lignin, cuticle and melanin. The role of quinone methides in these various processes is reviewed.

Airway inflammation induced by xanthine/xanthine oxidase in guinea pigs

Airway inflammation is suggested to play an important role in bronchial asthma. However, there is poor documentation about the effects of reactive oxygens on airway tissues in aspect of airway inflammation. Presently, we investigated whether aerosolized xanthine (X)/xanthine oxidase (XOD) induces airway inflammation in anesthetized guinea pigs. Inhalation of X for 5 min followed by inhalation of XOD for 5 min was performed with an ultrasonic nebulizer in anesthetized animals. Airway inflammation was assessed by airway vascular permeability using Pontamine sky blue. Inhalation of X/XOD produced a marked Pontamine sky blue exudation in the trachea, main bronchus and lungs. The X/XOD-induced increase in Pontamine sky-blue exudation was attenuated by pretreatment with inhaled catalase, but not by superoxide dismutase. Additionally, in the bronchus and lungs, the increase in Pontamine sky-blue exudation was significantly suppressed by deferoxamine. The above results indicate that hydrogen peroxide and hydroxyl radical converted from superoxide anion cause an intense airway inflammation.