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Second Exposure (second + exposure)
Selected AbstractsMacroinvertebrate community response to pulse exposure with the insecticide lambda-cyhalothrin using in-stream mesocosmsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2005Lars-Henrik Heckmann Abstract esticides are constantly beingapplied to agricultural catchments, but little is known abouttheir impact onaquatic biota during natural exposure. In the present study, the impact of the pyrethroid lambda-cyhalothrin was studied in an in-stream mesocosm setup. Twice during the summer of 2002, the natural macroinvertebrate community was exposed in situ to a 30-min pulse of lambda-cyhalothrin. Pyrethroid doses were released through a modified drip set with nominal concentrations of 0.10, 1.00, and 10.0 ,g L,1 during the first exposure and 0.05, 0.50, and 5.00 ,g L,1 in the second exposure. Before, during, and after exposure, drifting macroinvertebrates were caught in nets. Quantitative benthic samples were taken both before and on two occasions after exposure. Macroinvertebrate drift increased immediately after the pulse exposure, with total drift being significantly higher at all concentrations. Gammarus pulex, various Ephemeroptera, Leuctra sp., and Simuliidae were some of the taxa showing the most pronounced drift response. Structural change in the community was found only at 5.00 and 10.0 ,g L,1, and recovery occurred within approximately two weeks. The present study may be valuable in assessing extrapolations based on laboratory results as well as in evaluating pyrethroid impact on natural freshwater environments. [source] Aspirin sensitivity: acetylsalicylate or excipientsINTERNAL MEDICINE JOURNAL, Issue 8 2009B. S. Hebron Abstract We present three patients who developed urticaria while taking an enteric formulation of aspirin, confirmed on a second exposure. Although hypersensitivity reactions to aspirin, especially in asthmatic patients or those with nasal polyps, are well reported, our patients did not exhibit any underlying history of atopy. Furthermore, two of the patients were able to tolerate a soluble formulation. We review the literature and discuss whether these symptoms might be caused by pharmaceutical excipients, present in very small amounts in the enteric coating, rather than the active ingredient acetylsalicylate. Adverse reactions to excipients are fortunately rare but are occasionally reported. [source] Effects of high-intensity focused ultrasound on the intervertebral disc: A potential therapy for disc herniationsJOURNAL OF CLINICAL ULTRASOUND, Issue 7 2006Carina Forslund PhD Abstract Purpose. To determine the potential application of high-intensity focused ultrasound for the minimally invasive treatment of herniated intervertebral discs by developing a probe that produces sufficiently high temperature locally to shrink collagen fibers (65,75°C). Materials and Methods. A 5-mm ultrasound probe was produced with a geometric focal length of 15 mm. The probe produced 2.5 W of acoustic power and was operated at a frequency of 4.1 MHz. Measurements of temperature increase were performed in discs from bovine tails. In vivo experiments were performed to assess histologic changes in the disc as well as in nerve root and muscle. Results. Sufficient temperature increase to produce collagen shrinkage was observed close to the focus of the ultrasound. Temperature measurements in vertebral end plates showed a temperature increase of only 4°C after 60-second exposure of the disc. In vivo experiments revealed histologic changes in the disc consistent with collagen shrinkage, with no adverse effects seen in surrounding tissues. Conclusions. The experiments demonstrated the feasibility of high-intensity focused ultrasound in the treatment of contained herniated discs. This technique has several advantages over other thermal treatment modalities. © 2006 Wiley Periodicals, Inc. J Clin Ultrasound 34:330,338, 2006 [source] Longevity and fecundity of Eulophus pennicornis, an ectoparasitoid of the tomato moth Lacanobia oleracea, is affected by nutritional state and diet qualityAGRICULTURAL AND FOREST ENTOMOLOGY, Issue 1 2010Maureen E. Wakefield 1Adult female Eulophus pennicornis require a source of nutrition, provided by sources such as pollen, nectar and honeydew or by host feeding, to promote longevity and facilitate egg production. There is potential for parasitoids to be exposed directly to contaminants, including gene products in transgenic crops, through feeding on plant materials, honeydew or hosts. Among such potential contaminants are lectins such as Galanthus nivalis agglutinin (GNA) and concanavalin agglutinin (Con A). 2The effect of direct exposure to honey diets containing GNA and Con A on the longevity and fecundity of E. pennicornis was examined. These lectins have been expressed in a number of plant species for the control for various insect pests. Both GNA and Con A significantly reduced longevity and fecundity at the highest concentration used (0.5% w/v). The effect on fecundity was shown to be related to a reduction in longevity. 3Examination of the gustatory response of adult female E. pennicornis to honey diet containing 1% w/v GNA or Con A revealed no significant differences in consumption rate on first exposure. A significant reduction in the time spent feeding on diet containing 1% Con A was found on the second exposure to the diet. This could have been the result of either a conditioned aversion response or the intoxication of the insect. The effect of Con A on longevity and fecundity could have been, in part, a result of reduced food intake. 4Studies on nutrition and egg resorption demonstrated that the availability of honey solution prolongs the longevity of E. pennicornis and the lack of a source of nutrition promotes oosorption. 5A greater understanding of feeding behaviour and ovigeny is required to understand fully the potential ecological consequence of transgenic crops on parasitoid species through routes of direct exposure to transgene products. [source] An Assay for Evoked Locomotor Behavior in Drosophila Reveals a Role for Integrins in Ethanol Sensitivity and Rapid Ethanol ToleranceALCOHOLISM, Issue 10 2009Poonam Bhandari Background:, Ethanol induces similar behavioral responses in mammals and the fruit fly, Drosophila melanogaster. By coupling assays for ethanol-related behavior to the genetic tools available in flies, a number of genes have been identified that influence physiological responses to ethanol. To enhance the utility of the Drosophila model for investigating genes involved in ethanol-related behavior, we explored the value of an assay that measures the sedative effects of ethanol on negative geotaxis, an evoked locomotor response. Methods:, We established eRING (ethanol Rapid Iterative Negative Geotaxis) as an assay for quantitating the sedative effects of ethanol on negative geotaxis (i.e., startle-induced climbing). We validated the assay by assessing acute sensitivity to ethanol and rapid ethanol tolerance in several different control strains and in flies with mutations known to disrupt these behaviors. We also used eRING in a candidate screen to identify mutants with altered ethanol-related behaviors. Results:, Negative geotaxis measured in eRING assays was dose-dependently impaired by ethanol exposure. Flies developed tolerance to the intoxicating effects of ethanol when tested during a second exposure. Ethanol sensitivity and rapid ethanol tolerance varied across 4 control strains, but internal ethanol concentrations were indistinguishable in the 4 strains during a first and second challenge with ethanol. Ethanol sensitivity and rapid ethanol tolerance, respectively, were altered in flies with mutations in amnesiac and hangover, genes known to influence these traits. Additionally, mutations in the , integrin gene myospheroid and the , integrin gene scab increased the initial sensitivity to ethanol and enhanced the development of rapid ethanol tolerance without altering internal ethanol concentrations. Conclusions:, The eRING assay is suitable for investigating genetic mechanisms that influence ethanol sensitivity and rapid ethanol tolerance. Ethanol sensitivity and rapid ethanol tolerance depend on the function of , and , integrins in flies. [source] Effects of the Glucocorticoid Antagonist, Mifepristone, on the Consequences of Withdrawal From Long Term Alcohol ConsumptionALCOHOLISM, Issue 12 2008Catherine Jacquot Background:, Studies were carried out to test the hypothesis that administration of a glucocorticoid Type II receptor antagonist, mifepristone (RU38486), just prior to withdrawal from chronic alcohol treatment, would prevent the consequences of the alcohol consumption and withdrawal in mice. Materials and Methods:, The effects of administration of a single intraperitoneal dose of mifepristone were examined on alcohol withdrawal hyperexcitability. Memory deficits during the abstinence phase were measured using repeat exposure to the elevated plus maze, the object recognition test, and the odor habituation/discrimination test. Neurotoxicity in the hippocampus and prefrontal cortex was examined using NeuN staining. Results:, Mifepristone reduced, though did not prevent, the behavioral hyperexcitability seen in TO strain mice during the acute phase of alcohol withdrawal (4 hours to 8 hours after cessation of alcohol consumption) following chronic alcohol treatment via liquid diet. There were no alterations in anxiety-related behavior in these mice at 1 week into withdrawal, as measured using the elevated plus maze. However, changes in behavior during a second exposure to the elevated plus maze 1 week later were significantly reduced by the administration of mifepristone prior to withdrawal, indicating a reduction in the memory deficits caused by the chronic alcohol treatment and withdrawal. The object recognition test and the odor habituation and discrimination test were then used to measure memory deficits in more detail, at between 1 and 2 weeks after alcohol withdrawal in C57/BL10 strain mice given alcohol chronically via the drinking fluid. A single dose of mifepristone given at the time of alcohol withdrawal significantly reduced the memory deficits in both tests. NeuN staining showed no evidence of neuronal loss in either prefrontal cortex or hippocampus after withdrawal from chronic alcohol treatment. Conclusions:, The results suggest mifepristone may be of value in the treatment of alcoholics to reduce their cognitive deficits. [source] Cloning and identification of EDD gene from ultraviolet-irradiated HaCaT cellsPHOTODERMATOLOGY, PHOTOIMMUNOLOGY & PHOTOMEDICINE, Issue 6 2006Nishma Gupta Ultraviolet (UV) radiation is one of the most important external stimuli that affects skin by inducing cancer, inflammation and cell death. To identify the regulation of genes regulated by UV during transformation, normal human keratinocyte cell line, HaCaT, was exposed to multiple doses of UVA+B (UVA , 150,200 mJ/cm2 and UVB , 15,20 mJ/cm2× 6). Malignant transformation was confirmed by formation of colonies on soft agar and DNA methylation assay. To identify the genes involved in this process, random amplification of polymorphic DNA using RNA from unexposed and multiple exposed cells was performed after each exposure. A few up-regulated genes were identified, cloned and sequenced. One of the genes had homology to EDD (E3 identified by differential display) that was up-regulated at second exposure but was down-regulated in colony-forming cells (cells that received six or more exposures) as determined by RT-PCR. This is a progesterone-induced gene and progesterone treatment reduced the extent of colony formation on soft agar plate. It is possible that hormone therapy may have some effects on skin cancer in vivo. [source] An In Vitro Investigation of a Comparison of Bond Strengths of Composite to Etched and Air-Abraded Human Enamel SurfacesJOURNAL OF PROSTHODONTICS, Issue 1 2006G.B. Gray BDS Purpose: The purposes of the study were to measure the tensile bond strength of composite resin to human enamel specimens that had been either etched or air-abraded, and to compare the quality of the marginal seal, through the assessment of microleakage, of composite resin to human enamel specimens that had been either etched or air-abraded. Materials and Methods: Thirty mandibular molar teeth were decoronated and sectioned mesio-distally to produce six groups, each containing ten specimens that were embedded in acrylic resin using a jig. In each of the four treatment groups, the specimen surfaces were treated by either abrasion with 27 or 50 ,m alumina at 4 mm or 20 mm distance, and a composite resin was bonded to the treated surfaces in a standardized manner. In the two control groups the specimens were treated with 15 seconds exposure to 36% phosphoric acid gel and then similarly treated before being stored in sterile water for 1 week. All specimens were then subjected to tensile bond strength testing at either 1 or 5 mm/min crosshead speed. For the microleakage study, the degree of dye penetration was measured 32 times for each treatment group, using a neutral methylene blue dye at the interface between composite and either 27 or 50 ,m air-abraded tooth structure or etched enamel surfaces. Results: The mean bond strength values recorded for Group 1 (phosphoric acid etch, 5 mm/min crosshead speed) was 25.4 MPa; Group 2 (phosphoric acid etch, 1 mm/min), 22.2 MPa; Group 3 (27 ,m alumina at 4 mm distance), 16.8 MPa; Group 4 (50 ,m alumina at 4 mm distance), 16.9 MPa; Group 5 (27 ,m alumina at 20 mm distance), 4.2 MPa; and for Group 6 (50 ,m alumina at 20 mm distance) 3.4 MPa. An analysis of variance (ANOVA) demonstrated significant differences among the groups, and a multiple comparison test (Tukey) demonstrated that conventionally etched specimens had a greater bond strength than air-abraded specimen groups. No significant difference in dye penetration could be demonstrated among the groups (p= 0.58). Conclusions: Composite resin applied to enamel surfaces prepared using an acid etch procedure exhibited higher bond strengths than those prepared with air abrasion technology. The abrasion particle size did not affect the bond strength produced, but the latter was adversely affected by the distance of the air abrasion nozzle from the enamel surface. The crosshead speed of the bond testing apparatus had no effect on the bond strengths recorded. The marginal seal of composite to prepared enamel was unaffected by the method of enamel preparation. [source] | ||||||||||