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At least 127 records · Page 7Linked to original sources
PubMed2004

A model system to study the environment-dependent expression of the Bet v 1a gene encoding the major birch pollen allergen.

BACKGROUND: The major birch pollen allergen Bet v 1 (or Bet v 1a) is one of the main causes of seasonal type I allergies. Various environmental factors such as light, temperature and air pollution may influence the activity of the Bet v 1a gene. The creation of a model system to evaluate the role of environmental factors affecting the Bet v 1a gene expression would be highly desirable. We suggest the use of transgenic tobacco plants carrying a Bet v 1a promoter-reporter gene fusion as such a system. METHODS: The promoter of the Bet v 1a gene was isolated with the use of the Universal Genome Walker kit (BD Biosciences Clontech, USA). Web Software was used to search for putative cis-regulatory elements within the promoter. Transgenic tobacco plants harboring the promoter-beta-glucuronidase (GUS) reporter gene fusion were obtained via Agrobacterium tumefaciens-mediated transformation. Promoter activity was examined with histochemical and quantitative assays. RESULTS: Structural analysis predicted elements responsible for pollen-specific, light-, stress- and hormone-mediated induction within the Bet v 1a promoter. The evaluation of GUS activity in transgenic tobacco plants showed that the Bet v 1a promoter is pollen-specific. Moreover, the Bet v 1a promoter is considered to be the strongest isolated pollen-specific promoter reported to date. It was shown that temperature and abscisic acid positively regulate the activity of the Bet v 1a promoter during pollen development, providing evidence for environment-dependent regulation of the Bet v 1a gene. CONCLUSIONS: A model system to study the effect of environmental factors on the expression of the Bet v 1a gene encoding the major birch allergen in pollen was generated. Additionally, we suggest that this system could be used to search for factors that inhibit the activity of the gene in pollen in order to reduce the potential allergenicity of birch trees.

Abscisic Acid↗
PubMed2000

Aerosol light scattering measurements as a function of relative humidity.

The hygroscopic nature of atmospheric fine aerosol was investigated at a rural site in the Great Smoky Mountains National Park during July and August 1995. Passing the sample aerosol through an inlet, which housed an array of Perma Pure diffusion dryers, controlled the sample aerosol's relative humidity (RH). After conditioning the aerosol sample in the inlet, the light scattering coefficient and the aerosol size distribution were simultaneously measured. During this study, the conditioned aerosol's humidity ranged between 5% < RH < 95%. Aerosol response curves were produced using the ratio bspw/bspd; where bspw is the scattering coefficient measured at some RH greater than 20% and bspd is the scattering coefficient of the "dry" aerosol. For this work, any sample RH values below 15% were considered dry. Results of this investigation showed that the light scattering ratio increased continuously and smoothly over the entire range of relative humidity. The magnitude of the ratio at a particular RH value, however, varied considerably in time, particularly for RH values greater than approximately 60%. Curves of the scattering coefficient ratios as a function of RH were generated for each day and compared to the average 12-hour chemical composition of the aerosol. This comparison showed that for any particular RH value the ratio was highest during time periods of high sulfate concentrations and lowest during time periods of high soil or high organic carbon concentrations.

Aerosols↗
PubMed2006

Photoirradiation of polycyclic aromatic hydrocarbons with UVA light - a pathway leading to the generation of reactive oxygen species, lipid peroxidation, and dna damage.

Polycyclic aromatic hydrocarbons (PAHs) are a class of genotoxic environmental contaminants. We have long been interested in determining the mechanisms by which PAHs induce genotoxicity. Although the metabolic activation of PAHs leading to biological activities has been well studied, the photo-induced activation pathway has seldom reported. In this paper, we review the study of photoirradiation of PAHs with UVA irradiation results in (i) cytotoxicity and DNA damage (ii) DNA single strand cleavage; (iii) formation of 8-hydroxy-2'-deoxyguanosine adduct (8-OHdG), and (iv) formation of lipid peroxidation. Evidence has been shown that these photobiological activities are mediated by reactive oxygen species (ROS).

DNA Adducts↗
PubMed2000

Evaluation of some air pollution indicators in Turkey.

This article intends to shed a light on air quality in Turkey and compare air pollutant emissions on a national scale with that of the European countries. In order to estimate the quantities of Turkish emissions in the past and their future predictions, a national emission inventory was prepared with respect to five major pollutants consisting of particulate matter(PM), SOx, NOx, non-methane volatile organic compounds, and CO with 5-year intervals between 1985 and 2005. The results suggest that Turkey is a rather large emission source at the European scale, although emission indicators on unit area and per capita were shown to be somewhat smaller in magnitude. Levels of air pollution in some of the big cities in Turkey were also evaluated from available national monitoring data. These evaluations for the urban air qualities covered SO2 and PM parameters between 1986 and 1996, and results were compared with the present Turkish air quality limits, their probable revisions, WHO (Europe) guidelines and related EC directives. Results showed that the air quality limits were not met, especially during the winter periods in Turkish cities. Urban air pollutants characterizing the air in Turkish cities other than SO2 and PM, however, could not have been evaluated as these pollutants were not systematically monitored in these cities.

Air Pollutants↗
PubMed1995

Photodecomposition of 1,2,3,4- and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in water-alcohol media on a solid support.

We used a hydrophobic solid support, octadecylsilylated silica gel (C18), packed in a quartz column as a reaction medium for the photolysis of 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) and 1,2,3,4-tetrachlorodibenzo-p-dioxin (1,2,3,4-TCDD). When we exposed the column to a 450 W UV lamp, the adsorbed 1,2,3,4-TCDD or 2,3,7,8-TCDD in 10% 2-propanol/water decomposed completely in 20 minutes and 5 minutes, respectively. The large estimated partition coefficient of 1,2,3,4-TCDD in 10% 2-propanol/water (> 1000) indicates that on the C18 stationary phase, both the saturated hydrocarbon chains and the absorbed 2-propanol may act as proton donors and accelerate the photolysis. In direct sunlight, the adsorbed 1,2,3,4-TCDD in 10% 2-propanol/water decomposed much faster than in a nonaqueous solvent (50% 2-propanol/methanol). This solvent effect is advantageous for the practical use of the C18 photolysis process in aqueous waste treatment. We have demonstrated that complete C18 trapping with continuous photodecomposition of TCDD contained in an aqueous alcohol waste is possible.

Adsorption↗
PubMed1975

Dust counting. Critical review and presentation of Vermont practice.

Counting respirable dust particles using bright field microscopy has been the classic approach for rapid practical evaluation of the dustiness of workplace atmospheres. The technique has been beset with difficulties arising out of variations in the optical systems and the counting cells used by various laboratories. This papar reviews the history of the technique and some of the problems which have been encountered. It also details the method used by the Vermont Division of Occupational Health for the past 20 years to count dust, describing the easily reproducible optical system and the use of a "thin" hemocytometer cell employed.

Air Pollution↗
PubMed1988

Multivariate patterns of algal sensitivity to chemicals in relation to phylogeny.

Species-dependent variations in algal sensitivity make predictions from conventional algal growth tests uncertain. The use of test batteries comprising several unialgal tests improves the predictive value drastically. To select the members for an optimal test battery is a multivariate problem. To be an efficient member of the battery a species should have a sensitivity pattern that is complementary to the other members. Sensitivity patterns were analyzed with a principal component method (SIMCA). Toxicity data for 19 chemical compounds and 16 microalgal strains were used as input in the analysis. Two separate groups with significantly different sensitivity patterns were recognized, belonging to Chlorococcales and Cyanophyta, respectively. No algal species, belonging to other taxa of Chlorophyta or to Xanthophyta, had sensitivity patterns that fitted into any of the two groups. It is concluded that the phylogeny of the algae is toxicologically relevant and as a tentative strategy for test battery design we suggest that a taxonomically wide range of algal species should be used.

Cyanobacteria↗
PubMed1988

Phototaxis in aquatic invertebrates: possible use in ecotoxicity tests.

A series of experiments has been carried out aimed at (i) a deeper study of the phototaxis of some aquatic invertebrates and (ii) its possible use in ecotoxicity tests. For the first point the phototaxis of the nauplii of Artemia salina was examined: through tests carried out under different conditions, it was observed that a marked complex response to light existed, which led to a subdivision between individuals with different phototactic response, mainly depending on the density of the nauplii, on light intensity, and on spectral composition. The second point has been analyzed with A. salina, Daphnia magna, and Aëdes aegypti. For the first species it must be stressed that in ecotoxicity tests carried out with nauplii of A. salina one should bear in mind the complexity of their phototactic response. With D. magna and A. aegypti a simple pvc apparatus connected with optic fibers and set up on a microscope was used. The result is marked and easily observable; therefore, it will be possible in the future to perform easily tests with toxic substances which are important in ecotoxicology.

Aedes↗
PubMed2001

The potential for short rotation energy forestry on restored landfill caps.

This review examines the potential for producing biomass on restored landfills using willow and poplar species in short rotation energy forestry. In southern England, the potential production may be about 20 t ha(-1) of dry stem wood annually. However, actual yields are likely to be constrained by detrimental soil conditions, including shallow depth, compaction, low water holding capacity and poor nutritional status. These factors will affect plant growth by causing drought, waterlogging, poor soil aeration and nutritional deficiencies. Practical solutions to these problems include the correct placement and handling of the agricultural cap material, soil amelioration using tillage and the addition of organic matter (such as sewage sludge), irrigation (possibly using landfill leachate), the installation of drainage and the application of inorganic fertilizers. The correct choice of species and clone, along with good site management are also essential if economically viable yields are to be obtained. Further investigations are required to determine the actual yields that can be obtained on landfill sites using a range of management inputs.

Agriculture↗
PubMed1999

Morphological Developmental Stability in Plants: Patterns and Causes.

Minor bilateral or radial asymmetry of leaves or flowers, the frequency of phenodeviants, intraindividual variation in repeated characters, and fractal dimensions of morphology are considered to represent measures of developmental instability since deviations from regularity of the phenotype constitute a measure of the inability to maintain developmental precision during ontogeny. First, we review patterns of fluctuating asymmetry in plants and show that levels of asymmetry are considerably greater than in animals. While petal asymmetry tends to decrease with petal size within species, leaf asymmetry tends to increase with leaf size. Intraspecific correlations of petal asymmetry and leaf asymmetry are weakly positive. Second, a meta-analysis of the effects of environmental factors hypothesized to increase asymmetry in leaves and flowers, such as radiation, ultraviolet light, excess artificial fertilizer, pollutants, extreme saline conditions, herbivory, and competition, showed intermediate (i.e., explaining 10% of the variance) to large (i.e., explaining 25% of the variance) effects. Third, a meta-analysis of the effects of genetic factors hypothesized to contribute to increased asymmetry in plants, such as homozygosity, hybridization, mutation, and quantitative genetic differences among individuals, showed variable but usually significant effects, although the number of studies generally was small. Controlled experimental studies of environmental and genetic effects on developmental instability of plants may increase our understanding of the mechanisms causing developmental instability.

Journal Article↗
PubMed2006

[Developmental centered care. Evaluation of Spanish neonatal units].

INTRODUCTION: Developmental and family centered care (DC) is a framework that aims to enhance the neurodevelopment of the infant. Over the last few years Spanish neonatal units have been working toward introducing this type of care. OBJECTIVE: To evaluate DC in Spanish neonatal units by assessing certain features of the care provided to very low birth weight infants and their families. MATERIAL AND METHOD: Spanish hospitals attending infants under 1,500 g were identified. A cross sectional study was performed using a telephone questionnaire with 25 DC-related items. RESULTS: Of the 100 hospitals attending infants under 1,500 g, 83 hospitals from all the Autonomous Communities in Spain participated in the survey. Of these, 31 % had noise pollution controls, 72 % controlled light intensity, 75 % bound the infants, and 29 % used saccharose as an analgesic. Ten percent allowed unrestricted parental visits. Twenty-two percent used kangaroo care without restriction. Sixty-three percent of the units reported difficulties when introducing DC-related changes. CONCLUSIONS: Practically all neonatal units have some type of DC activity, although in certain areas, such as unrestricted parental visits, the rate of implementation is low.

Cross-Sectional Studies↗