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Response Differences (response + difference)
Selected AbstractsCoupling Short-Term Changes in Ambient UV-B levels with Induction of UV-Screening Compounds,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2007Joe H. Sullivan ABSTRACT A substantial number of studies have been conducted over the last several decades to assess the potential impacts of long-term increases in ultraviolet-B radiation (UV-B between 280 and 320 nm) that will result from continued depletion of stratospheric ozone. However, seasonal changes, tropospheric chemistry and cloudiness are the dominant factors controlling ambient UV-B levels on a short-term or daily basis. The effects of short-term changes in UV-B on plant growth, phytochemistry and physiological processes have received relatively little attention. The USDA UV-B Monitoring and Research Program provides an excellent network of stations that provide an opportunity to monitor long-term changes in solar UV-B radiation and evaluate the responses of plants to short-term variation in UV-B levels on a near-real-time basis. In this study barley (Hordeum vulgare L.) and soybean (Glycine max [L] Merr.) were used as model systems. Emerging seedlings of these species were grown under either near-ambient levels of UV-B or under reduced levels (ca 90% reduction) in the field. Periodic measurements of foliar UV-screening compounds were made on separate groups of seedlings planted at intervals over the growing season during contrasting periods of ambient levels of UV radiation. The levels of UV-screening compounds correlated with UV-B levels in both species and with UV-A in soybean but the sensitivity of the response differed between the two species and among the soybean cultivars. Response differences among species may be related to unique secondary chemistry of each species, so one response estimate or action spectrum may not be appropriate for all species. [source] Diapause disruption with tebufenozide for early-instar control of the spruce budworm, Choristoneura fumiferanaPEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 8 2007Daniel Doucet Abstract In North America, the eastern spruce budworm, Choristoneura fumiferana Clem., is an important coniferous pest against which tebufenozide has proven effective as a control product. By acting as an ecdysone agonist, tebufenozide can induce precocious moulting in late (fifth,sixth) instars but can also be carried over to the next generation owing to its persistence on foliage. The authors conducted laboratory experiments on first-instar larvae treated with tebufenozide dissolved in acetone. Larvae exposed to doses equal to or above 0.1 µg cm,2 displayed precocious moulting in the second instar after hibernaculum spinning, which effectively disrupted diapause. Larger doses induced moulting in first instars. Evidence is provided that this dose,response difference is related to whether or not an effective dose of tebufenozide is ingested by the first instar prior to the peak of moulting hormone (20-hydroxyecdysone) in first instars. Doses ineffective to kill first instars are carried over to the second instar, where they induce a precocious moult. This type of response to tebufenozide is dependent on the presence of a moulting machinery (the EcR,USP receptor complex) that is ready for ecdysone transduction. Interestingly, ecdysone levels are low in second instars, as measured by a radioimmunoassay, which suggests that diapause in spruce budworm is maintained by a suppression of ecdysone production. Thus, diapause disruption by tebufenozide may well provide an alternative control strategy for this important pest. Copyright © 2007 Society of Chemical Industry [source] Spatial and temporal analysis of fMRI data on word and sentence readingEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 7 2007Sven Haller Abstract Written language comprehension at the word and the sentence level was analysed by the combination of spatial and temporal analysis of functional magnetic resonance imaging (fMRI). Spatial analysis was performed via general linear modelling (GLM). Concerning the temporal analysis, local differences in neurovascular coupling may confound a direct comparison of blood oxygenation level-dependent (BOLD) response estimates between regions. To avoid this problem, we parametrically varied linguistic task demands and compared only task-induced within-region BOLD response differences across areas. We reasoned that, in a hierarchical processing system, increasing task demands at lower processing levels induce delayed onset of higher-level processes in corresponding areas. The flow of activation is thus reflected in the size of task-induced delay increases. We estimated BOLD response delay and duration for each voxel and each participant by fitting a model function to the event-related average BOLD response. The GLM showed increasing activations with increasing linguistic demands dominantly in the left inferior frontal gyrus (IFG) and the left superior temporal gyrus (STG). The combination of spatial and temporal analysis allowed a functional differentiation of IFG subregions involved in written language comprehension. Ventral IFG region (BA 47) and STG subserve earlier processing stages than two dorsal IFG regions (BA 44 and 45). This is in accordance with the assumed early lexical semantic and late syntactic processing of these regions and illustrates the complementary information provided by spatial and temporal fMRI data analysis of the same data set. [source] Viral dynamics and response differences in HCV-infected African American and white patients treated with IFN and ribavirinHEPATOLOGY, Issue 6 2003Jennifer E. Layden-Almer Studies have suggested that African American patients infected with hepatitis C virus (HCV) do not respond as well to treatment with interferon (IFN) as white patients. Here we analyzed the difference in the viral kinetic response between genotype 1 HCV-infected African American patients (n = 19) and white patients (n = 16). Patients were treated with 10 mIU IFN-,2b daily with or without ribavirin for 1 month followed by 3 mIU IFN-,2b 3 times a week with ribavirin. The kinetic parameters (,, treatment effectiveness at inhibiting virion production; ,, loss rate of virus-producing cells; c, clearance rate of free virions; ,, delay until viral decline starts) were estimated from the viral load decay profiles using a previously described mathematical model. Differences in early kinetic parameters and viral negativity frequencies at weeks 4, 12, and 48 were compared. Ribavirin did not appear to enhance any of the viral kinetic parameters, although this may have been due to the high dose of IFN used. African American patients exhibited significantly (P = .005) lower drug effectiveness (88.6% vs. 98.2%) compared with white patients, accounting for a 0.8 log lower HCV RNA decrease in the first 24 hours of treatment. Significant differences (P = .006) were also noted for ,. There was no correlation between any of the viral kinetic parameters and either age, body mass index (BMI), or genotype 1 subtype. No patient achieved viral negativity at weeks 4, 12, or 48 without an , greater than 90%. The mean viral decline and viral negativity rates were statistically different between the two races; however, when controlling for treatment effectiveness, these differences were no longer apparent. In conclusion, the failure of IFN response in African American patients infected with genotype 1 HCV is in part due to an impaired ability to inhibit viral production. [source] Blood Oxygen Level Dependent Response and Spatial Working Memory in Adolescents With Alcohol Use DisordersALCOHOLISM, Issue 10 2004Susan F. Tapert Background: Previous studies have suggested neural disruption and reorganization in young and older adults with alcohol use disorders (AUD). However, it remains unclear at what age and when in the progression of AUD changes in brain functioning might occur. Methods: Alcohol use disordered (n= 15) and nonabusing (n= 19) boys and girls aged 15 to 17 were recruited from local high schools. Functional magnetic resonance imaging data were collected after a minimum of 5 days' abstinence as participants performed spatial working memory and simple motor tasks. Results: Adolescents with AUD showed greater brain response to the spatial working memory task in bilateral parietal cortices and diminished response in other regions, including the left precentral gyrus and bilateral cerebellar areas (clusters ,943 ,l; p < 0.05), although groups did not differ on behavioral measures of task performance. No brain response differences were observed during a simple finger-tapping task. The degree of abnormality was greater for teens who reported experiencing more withdrawal or hangover symptoms and who consumed more alcohol. Conclusions: Adolescents with AUD show abnormalities in brain response to a spatial working memory task, despite adequate performance, suggesting that subtle neuronal reorganization may occur early in the course of AUD. [source] The host cytokine response to Porphyromonas gingivalis is modified by gingipainsMOLECULAR ORAL MICROBIOLOGY, Issue 1 2009P. G. Stathopoulou Background/aims:, Clinical studies indicate that primary proinflammatory cytokines, such as interleukin-1, (IL-1,) are elevated in the gingival crevice around teeth with periodontitis but the secondary cytokines and chemokines, IL-6 and IL-8, are not. The human gingival epithelial cells (HGECs) lining the gingival sulcus respond to perturbation by microbes of dental plaque by releasing a wide range of cytokines. Porphyromonas gingivalis, a putative periodontal pathogen, possesses numerous virulence factors some of which directly impact on the host response. In the present study, we sought to determine how P. gingivalis influences the inflammatory cytokine responses. Methods:, HGECs were challenged with P. gingivalis and other putative periodontal pathogens, and the resultant production of IL-1,, IL-6, and IL-8 was assayed by enzyme-linked immunosorbent assay (ELISA). Culture supernatants and recombinant human cytokines were challenged with live P. gingivalis wild-type and gingipain-deficient strains and the resultant cytokine profile was assessed by ELISA and Western blot. Results:, We show here that primary HGECs challenged with live P. gingivalis result in high levels of IL-1, but not the related secondary cytokines IL-6 and IL-8. We further demonstrate that cytokine response differences are the result of the action of P. gingivalis proteases, with lysine gingipain being the most effective. Conclusion:, We conclude that P. gingivalis, through lysine gingipain, can subvert the protective host proinflammatory response by direct cytokine degradation. Changes in the crevicular cytokine profile have consequences in periodontal disease pathogenesis that should be considered in the development of diagnostic and therapeutic modalities. [source] Temperament and stress response in children with juvenile primary fibromyalgia syndromeARTHRITIS & RHEUMATISM, Issue 10 2003Paola M. Conte Objective To examine temperament, stress response, child psychological adjustment, family environment, pain sensitivity, and stress response differences between children and adolescents with juvenile primary fibromyalgia syndrome (JPFMS), children with arthritis, and healthy controls. Parental psychological adjustment was also measured. Methods Subjects included 16 children with JPFMS, 16 children with arthritis, and 16 healthy controls. Participants completed the Dimensions of Temperament Survey-Revised (DOTS-R), State-Trait Anxiety Inventory, Children's Depression Inventory, Family Environment Scale (FES), Sensitivity Temperament Inventory for Pain (STIP), and Youth Self-Report. Responsiveness to an acute stressor was assessed by measuring salivary cortisol levels before and after venipuncture. Parents were asked to complete the parent versions of the DOTS-R, FES, STIP, Child Behavior Checklist, and Symptom Checklist-90-Revised. Results Children and adolescents with JPFMS demonstrated more temperamental instability, increased levels of depression and anxiety, less family cohesion, and higher pain sensitivity compared with the other 2 groups. Parents of children with JPFMS, in rating themselves, also reported higher levels of anxiety and depression, and lower overall psychological adjustment compared with parents of children in the other groups. Conclusion These results suggest that a psychobiologic perspective may contribute to an increased understanding of JPFMS in children and adolescents, facilitating an approach to investigating the interaction of factors that appear to place a child at risk for development of a pain syndrome. Because temperamental instability, sensitivity to pain, vulnerability to stress, psychological adjustment, family context, and parental psychopathology are individual risk factors, the interaction of these factors may explain the breadth of symptoms associated with this pain syndrome, as well as its severity. [source] | |||||||||||||