Diffusion of knowledge of Helicobacter pylori and its practical application by Nordic clinicians.

BACKGROUND: The knowledge uptake by physicians in five Nordic countries about Helicobacter pylori and gastrointestinal disease was studied. METHODS: Questionnaires were sent to 1832 general practitioners (GP) and gastroenterologists (GE), and central persons were interviewed in Norway, Sweden, Denmark, Finland, and Iceland. RESULTS: Half the GEs had heard of H. pylori by 1987 and had begun eradication treatment before 1991, and half the GPs had by 1989 and 1992, respectively. By 1996 this applied to more than 90% of both groups. The most important information sources were national journals for GPs and international journals and conferences for GEs. More than 80% of respondents considered H. pylori causative for peptic ulcer, less than 50% for stomach cancer, and 10% for non-ulcer dyspepsia. Variations between countries were mostly small. CONCLUSIONS: GPs and GEs in the Nordic countries have knowledge of H. pylori, and there is broad agreement on diagnosis and treatment, although some differences exist.

[Gaining new knowledge in clinical practice]. / Opptak av ny kunnskap i klinisk praksis.

A study of the diffusion of knowledge about Helicobacter pylori and gastrointestinal disease among Norwegian clinicians is reported. A questionnaire about when and how research results on Helicobacter pylori and gastrointestinal disease were taken up by doctors in their practice was sent to 200 general practitioners and 200 medical and surgical gastroenterologists. This Norwegian study is part of a comparative study of the uptake process in the five Scandinavian countries which is planned to be published in an international journal. The specialists both heard of research results and started using new treatments earlier than the general practitioners. The main sources of information for the general practitioners were the national medical journal and courses or conferences, whilst the specialists obtained their information mainly from international journals and courses or conferences. The general practitioners were more likely to treat Helicobacter pylori positive dyspepsia and to use serology as a diagnostic tool, whilst the specialists were more likely to use breath tests and had a greater belief in the role of Helicobacter pylori as a cause of gastric cancer. The great majority of both groups knew of Helicobacter pylori as a cause of peptic ulcer disease, used antibiotics in its treatment, and preferred (referral to) endoscopic biopsy as the main diagnostic tool.

[Knowledge about Helicobacter pylori and antibiotic treatment of peptic ulcer. A model study of information dissemination and implementation of the new knowledge in clinical practice]. / Viden om Helicobacter pylori og antibiotikabehandling af ulcussygdom. Et modelstudie over informationsspredning og implementering af ny viden i klinisk adfaerd.

Dissemination of information concerning new knowledge on peptic ulcer disease caused by Helicobacter pylori and treatment with antibiotics was surveyed. In 1996 a questionnaire was mailed to 200 gastroenterologists and 200 general practitioners. Physicians enumerate national medical journals as the most frequent source of information about the relationship between Helicobacter pylori and gastrointestinal ulcer. Six years after the first publication in international journals, 44% of the doctors had noticed this relation. Nearly all physicians had introduced antibiotics in treatment af peptic ulcer disease ten to twelve years after first announcement. The gastroenterologists preferred international medical journals whereas general practitioners stated national medical journals were the most important sources of new knowledge. General practitioners lacked knowledge of published guidelines for treatment of peptic ulcer disease.

Airborne mutagens and carcinogens from cooking and other food preparation processes.

The common food preparation processes, frying, broiling and baking, can give rise to air pollutants that are known to be mutagenic and carcinogenic in animal tests. A large number of persons can be exposed to such fumes as cooking is performed in most households and in many commercial enterprises. Additional studies on the emissions from these processes and exposure measurements are needed. Epidemiological studies on occupationally-exposed cooks and bakers with respect to cancer are equivocal.

Bioassay of complex mixtures of indoor air pollutants.

The development of short-term genetic bioassays has made it possible to conduct mutagenicity studies on complex mixtures of indoor air pollutants. Although most of the studies have used the standard S. typhimurium/microsome reversion assay developed by Ames et al. (1975), the development of microsuspension mutagenesis methods (see Methods 18 and 19, this volume) has facilitated wider use of bioassays in indoor air pollution studies. It is clear from the studies reviewed here that environmental tobacco smoke is the major source of mutagens indoors. Other sources which produce significant, but much smaller, increases in indoor air mutagenicity include outdoor air and other indoor combustion sources (e.g., cooking, kerosene heaters and open fireplaces burning wood). These studies have been based on measurement of the bacterial mutagenicity of extracts from particulate matter. A limited number of reports, however, indicate that volatile and semi-volatile constituents of indoor air may also be mutagenic and deserve further study.

Design and implementation of a collaborative study of the mutagenicity of complex mixtures in Salmonella typhimurium.

In 1987, the International Programme on Chemical Safety (IPCS) in collaboration with the U.S. Environmental Protection Agency (U.S. EPA) and the U.S. National Institute of Standards and Technology (U.S. NIST) initiated an international collaborative study of the mutagenicity of complex environmental mixtures in the Ames Salmonella typhimurium mutation assay. The objectives of this study were: (1) to estimate the inter- and intra-laboratory variability associated with the extraction of mixtures for bioassay, (2) to estimate the inter- and intra-laboratory variability associated with the Salmonella typhimurium bioassay when applied to complex mixtures, and (3) to determine whether standard reference complex mixtures would be useful in mutagenicity studies and to evaluate whether reference or certified mutagenicity values determined from this collaborative study should be reported. The complex mixtures used in this study were selected from standard reference materials (SRMs) which had previously been issued by the U.S. NIST as SRM 1597 (coal tar), SRM 1649 (diesel particulate matter) and SRM 1650 (urban air particulate matter) with certified values for polycyclic aromatic hydrocarbons. These SRM complex mixtures are available to scientists as reference standards for analytical chemistry research and are under consideration as SRMs for mutagenicity studies of complex environmental mixtures. This paper briefly describes the final study design, protocol, selection of the complex mixtures, and implementation of this international study.

Indoor sources of mutagenic aerosol particulate matter: smoking, cooking and incense burning.

The emission of aerosol particles and their mutagenic activity as well as the emission of some gaseous pollutants has been studied experimentally in order to compare the emission from some indoor pyrolysis processes. Cigarette (tobacco and herbal) smoking, incense and mosquito-coil burning and frying of experimental lean minced pork emitted particulate matter. Their extracts were mutagenic in the Ames Salmonella test with TA98 and activation as well as, with a higher response, in a microsuspension test with the same strain and activation condition. The response of the particles from the smoking and burning processes varied from 3000 to 50,000 revertants per gram of smoked or burnt material in the conventional Salmonella test and from 50,000 to 350,000 revertants per gram in the microsuspension assay. The frying of lean minced pork gave an airborne emission of about 53 and 560 revertants per gram of fried pork, respectively, in the 2 assays. The frying of some common food items following cookbook recipes also emitted mutagenic aerosol particles but the emitted activity was less than that in the pork experiment. Carbon monoxide, isoprene and benzene were present in the emissions from the smoking and burning processes but were not detectable in the frying fumes. The results suggest that incense and mosquito-coil burning can cause indoor air pollution akin to that from cigarette smoking. Indoor air pollution from cooking requires further study.

Environmental tobacco smoke: overview of chemical composition and genotoxic components.

Tobacco smoke contains numerous compounds emitted as gases and condensed tar particles. The sidestream smoke emissions, which constitute the major part of environmental tobacco smoke (ETS), are generally larger than the mainstream smoke emissions. Many of the organic compounds, belonging to a variety of chemical classes, are known to be genotoxic and carcinogenic. These include the known constituents, alkenes, nitrosamines, aromatic and heterocyclic hydrocarbons and amines. Emission of sidestream smoke in indoor environments with relatively low ventilation rates can result in pollutant concentrations above those generally encountered in ambient air in urban areas. The chemical characteristics of ETS thus support the indications that exposure to ETS can be causally associated with the induction of several types of cancer.

Public exposure to environmental tobacco smoke.

Airborne particulate matter has been collected by personal samplers in public indoor areas and travel situations with environmental tobacco smoke pollution. Following extraction, the samples were assayed for mutagenicity in the presence of S9 with a sensitive microsuspension test using Salmonella TA98. The mutagenic responses of indoor air from public areas were much higher than those of ambient outdoor air. Depending on the circumstances, the mutagenic response varied in trains and airplanes but the results show that physical separation of non-smoking sections from smoking sections is necessary in order to achieve genuine non-smoking areas. Chemical fractionation and mutagenicity assay of the basic fraction show that Salmonella mutagenicity of airborne particulate matter might be used as a tobacco smoke-specific indicator, as the basic fraction of environmental tobacco smoke contains a large part of the mutagenic activity whereas this is not the case for outdoor ambient airborne particulate matter.

Ah receptor ligands in tobacco smoke.

Tar particulates from cigarette smoke contain compounds with affinity for the Ah receptor. The sidestream activity is larger than that of the mainstream with a ratio of about 5. The compounds causing the affinity appear in the neutral fraction after chemical fractionation excluding basic and acidic components as major contributors to the affinity. The affinity cannot be explained by benzo[a]pyrene and other polycyclic aromatic hydrocarbons but it might be caused by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and related compounds and by oxidized tryptophan derivatives.

Pyrolysing insecticidal coils: air pollution by polycyclic aromatic hydrocarbons and other mutagens detected by the Salmonella/microsome test.

Pyrolysing insecticidal coils, which are used commonly for their evaporative release of insecticidal amounts of pyrethrins, have been investigated with respect to the emission of airborne particles, their mutagenic activity in the Salmonella/microsome mutagenicity test and their polycyclic aromatic hydrocarbons (PAH) content. Emitted particles contain compounds that are mutagenic in the absence of exogenous activation, as well as components that require mammalian activation. The particles also contain a range of PAH, but their concentration cannot account for the mutagenic response with mammalian activation. The use of pyrolysing insecticidal coils in semi-enclosed spaces may cause air pollution by releasing mutagenic and carcinogenic compounds that are of a magnitude similar to that found in other air pollution situations.

Mutagenic determination of passive smoking.

The mutagenic activity of tobacco smoke has been further investigated with the plate-incorporation method and a microsuspension technique of the Ames Salmonella assay. The microsuspension test gives a higher response than the conventional plate incorporation test. It is possible to detect environmental tobacco smoke (ETS) in moderately smoky indoor environments by collection of particulate matter with personal low volume samplers followed by particle extraction and mutagenicity testing with the microsuspension assay.

Mutagenicity assay of emission extracts from wood stoves: comparison with other emission parameters.

The emission from wood stoves of several types of air pollutants has been measured under standardized burning conditions with emphasis on the amount of organic compounds and determination of the mutagenic activity with the Salmonella/microsome assay. The study corroborates earlier findings that conventional wood stoves can be a significant source of hydrocarbon and tar compounds in the ambient air. The emission of mutagenic compounds comprise both compounds requiring mammalian activation and compounds which are active in the test without exogenous activation. The mutagenicity tests show that nitroaromatic compounds are present in wood stove emissions, although the emission of nitrogen oxides is low. A wood stove constructed using the downdraft principle emitted much less hydrocarbons and tar, less mutagenic components and slightly less carbon monoxide than conventional wood stoves.

Environmental tobacco smoke: comparative characterization by mutagenicity assays of sidestream and mainstream cigarette smoke.

Mainstream cigarette smoke particles were collected by means of a smoking machine, and sidestream particles were collected from the room in which the smoking took place. The particles were extracted by sonication with acetone, and the extracts were solvent-exchanged to dimethyl sulfoxide. The samples were tested for mutagenicity in the Ames Salmonella/microsome assay. The mainstream extract is preferentially mutagenic in the presence of S9, with about 30,000 revertants/cigarette in TA98, but has little or no activity in its absence. The sidestream extract is also mutagenic in the presence of S9 with TA98, and this activity is mainly due to basic compounds. Sidestream smoke is also significantly mutagenic in the absence of S9 in the strain TA100 as well as in TA97 and TA104. This "direct" activity is due to components that are labile. The response of sidestream particles is 10,000-20,000 revertants/cigarette in TA98 + S9 and TA100-S9 when the collection is performed in a room where the particle concentration is modulated by deposition to surfaces. Sidestream particles collected on glass fiber filter and by electrostatic precipitation (ESP) with a commercial air cleaning device gave essentially the same mutagenic response, showing that ESP sampling may be an alternative to filter sampling for environmental tobacco smoke (ETS) in indoor environments. ESP sampling in children's rooms in smoking and nonsmoking homes showed that 5-10% of the tobacco smoke emitted in the smoking homes entered the child's room, demonstrating that diffusion of pollutants is faster than ventilation in modern buildings with low ventilation rates.