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Detectable Effects (detectable + effects)
Selected AbstractsLong-term neurologic and peripheral vascular toxicity after chemotherapy treatment of testicular cancer,CANCER, Issue 10 2010Jennifer L Glendenning MD Abstract BACKGROUND: Testicular cancer is curable in the majority of men, and persisting treatment toxicity is a concern. The authors report a cross-sectional study of the long-term effects of chemotherapy (C) on neurologic function and development of Raynaud phenomenon. METHODS: Seven hundred thirty-nine patients who were treated between 1982 and 1992 gave consent to enter the study. Patients were classified according to the receipt of C (n = 384) or no C (n = 355). Patients completed a general health questionnaire and a quality-of-life form (the European Organization for Research and Treatment of Cancer Quality-of-Life C30 questionnaire with testicular module). Symptom scores of 3 or 4 were considered clinically significant. Patients were assessed in the clinic, and clinical history was used to diagnose Raynaud phenomenon (RP) and tinnitus. Examinations included peripheral nerve function testing for light touch and vibration sense. Five hundred seventy-seven patients underwent audiometry. RESULTS: On physician assessment, peripheral neuropathy and RP were more common after C (21.7% vs 9.1% [P<.001] and 20.3% vs 1.7% [P<.001], respectively). Similar results were obtained for symptom scores (12.5% vs 5.5% [P = .002] and 9.7% vs 3.7% [P<.001], respectively). On multivariate analysis, for peripheral neuropathy, the significant predictors were cisplatin dose, carboplatin dose, and age. For RP, the significant predictor was bleomycin. Significant differences in hearing thresholds were noted at 8000 hertz only and, on multivariate analysis, were related to age, cisplatin dose, and vincristine dose. Auditory symptom scores did not differ between groups. CONCLUSIONS: With long-term follow-up, peripheral neuropathy and RP remained detectable in approximately 20% of patients and caused significant symptoms in 10% of patients. Detectable effects on high frequency remained but caused little symptomatic problem. These effects persisted and were related to the cumulative chemotherapy dose. Cancer 2010. © 2010 American Cancer Society. [source] Bottom-up, top-down, and within-trophic level pressures on a cactus-feeding insectECOLOGICAL ENTOMOLOGY, Issue 2 2008TOM E. X. MILLER Abstract 1.,The relative importance of host-plants and predators in the population dynamics of herbivorous insects, and the frequency and intensity of inter-specific competition among herbivores, have both been intensively studied and debated. The joint effects of bottom-up, top-down, and within-trophic level interactions, however, have rarely been integrated in a single system. 2.,I studied the dynamics of the cactus bug (Narnia pallidicornis), a specialist feeder on tree cholla cactus (Opuntia imbricata), in response to variable host-plant quality, spider predation, and interactions with cactus-feeding beetles (Moneilema appressum). Previous work suggests that cactus reproductive effort (the proportion of meristems allocated to reproduction) is an important component of host-plant quality for Narnia. I conducted a 2-year field experiment to test the hypotheses that Narnia abundance is positively related to host-plant reproductive effort, and that interactions with predators and putative competitors alter the shape of this relationship. 3.,I found strong support for the first prediction (positive Narnia,plant quality relationship) in both years, but neither predator removal nor beetle exclusion had detectable effects on this relationship in either year. I conclude that the dynamics of this insect herbivore are driven predominantly from the bottom-up, and that available data from this work and from previous studies are too variable to permit broad generalisations for the combined effects of host-plants, predation, and competition on herbivore dynamics. [source] Parasitism by the mite Trombidium breei on four U.K. butterfly speciesECOLOGICAL ENTOMOLOGY, Issue 6 2002L. Conradt Abstract 1. The incidence of parasitism by larvae of the mite species Trombidium breei was reported in one population of the lycaenid butterfly Polyommatus icarus, four populations of the satyrine butterfly Maniola jurtina, one population of the satyrine butterfly Aphantopus hyperanthus, and two populations of the satyrine butterfly Pyronia tithonus, as well as on one specimen of the dipteran Alophorus hemiptera. A considerable proportion of butterflies (11-50%) was infested in all study populations. 2. The pattern of infestation was examined in detail in M. jurtina. Males had a significantly higher incidence of infestation than females, and middle-aged butterflies had a higher incidence of infestation than old or young butterflies. The incidence of infestation peaked in the middle of the flight season, and this seasonal effect was independent of the effect of butterfly age. 3. Using a model based on capture-recapture data, it was estimated that a hypothetical ideal male M. jurtina that lives exactly the mean expected lifespan of 9-10 days has an approximately 75% chance of becoming infested with mites at least once during its lifetime, a mean time to first infestation of 3-4 days, and an average infestation persistence time of 2-3 days. 4. Capture-recapture data failed to show any effect of mite infestation on the lifespan or within-habitat movement rate of M. jurtina. 5. In experiments in which individual butterflies were taken out of their normal habitat and released, M. jurtina and P. tithonus that were infested with mite larvae did not differ from uninfested individuals in the efficiency with which they returned to suitable habitat. Thus, parasitism by T. breei larvae had no detectable effects on flight performance or orientation ability. 6. The results suggest that trombidiid mite larvae have limited potential in the biological control of insect pests. [source] Trophic control of grassland production and biomass by pathogensECOLOGY LETTERS, Issue 2 2003Charles E. Mitchell Abstract Current theories of trophic regulation of ecosystem net primary production and plant biomass incorporate herbivores, but not plant pathogens. Obstacles to the incorporation of pathogens include a lack of data on pathogen effects on primary production, especially outside agricultural and forest ecosystems, and an apparent inability to quantify pathogen biomass. Here, I report the results of an experiment factorially excluding foliar fungal pathogens and insect herbivores from an intact grassland ecosystem. At peak in control plots, 8.9% of community leaf area was infected by pathogens. Disease reduction treatment dramatically increased root production and biomass by increasing leaf longevity and photosynthetic capacity. In contrast, herbivory reduction had no detectable effects at the ecosystem or leaf scale. Additionally, biomass of foliar fungal pathogens in the ecosystem was comparable with that of insect herbivores. These results identify pathogens as potential regulators of ecosystem processes and promote the incorporation of pathogens into trophic theory. [source] Impact of chemical elicitor applications on greenhouse tomato plants and population growth of the green peach aphid, Myzus persicaeENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 3 2006Anthony J. Boughton Abstract Recent advances in the understanding of plant signaling pathways have opened the way for using elicitor-induced plant resistance as a tactic for protecting plants against arthropod pests. Four common elicitors of induced responses in tomato, Lycopersicon esculentum Mill. (Solanaceae), were evaluated with regard to phytotoxicity, induction of plant defensive proteins, and effects on population growth and fecundity of a common pest, the green peach aphid, Myzus persicae (Sulzer) (Homoptera: Aphididae). Ethephon and methyl jasmonate (MJ) treatments caused varying degrees of phytotoxicity. Ethephon caused pronounced changes in plant growth form and severe, dose-dependent negative impacts on plant growth and flowering. Effects with MJ were milder, but still caused temporary inhibition of development, leading to smaller plants and delayed flowering. The commercial elicitors benzothiadiazole (BTH) and harpin did not cause detectable phytotoxicity. The highest doses of ethephon and MJ significantly increased leaf peroxidase (POD) levels but only MJ treatments significantly increased polyphenol oxidase (PPO) levels. BTH and harpin had no detectable effects on POD and PPO. Populations of green peach aphids grew significantly more slowly on plants treated with BTH or MJ than on control plants or plants treated with harpin or ethephon. Slowed aphid population growth on BTH-treated plants was due to significant reductions in aphid fecundity, although this was independent of changes in time to onset of reproduction or time to death. Aphid fecundity was also reduced on MJ-treated plants relative to controls, but this difference was not statistically significant, suggesting that other mechanisms are involved in slowing aphid population growth on MJ-treated plants. Growth of aphid populations on plants treated with a MJ,BTH mixture was reduced almost as much as with treatments of MJ alone, suggesting that antagonism between JA-dependant and SA-dependent plant signaling pathways is only mild with regard to induced defenses against aphids. [source] In situ reproduction, abundance, and growth of young-of-year and adult largemouth bass in a population exposed to polychlorinated biphenylsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2004Dudley W. Reiser Abstract We conducted a two-year field study (2000,2001) in the Housatonic River, Massachusetts (USA) to determine if we could detect in situ population-level effects on largemouth bass (Micropterus salmoides) exposed to elevated levels of polychlorinated biphenyls (PCBs). Calculated whole-body PCB concentrations in adult bass in 2002 averaged 121 mg/kg (range = 34,556 mg/kg). Polychlorinated biphenyl concentrations in young-of-year (YOY) composites in 2000 and 2002 averaged 28 mg/kg (range = 21,41 mg/kg) and 19 mg/kg (range = 16,24 mg/kg), respectively. Laboratory studies of fish have reported PCB toxicity at exposure levels below and within the range of those found in the Housatonic River. We evaluated five field-derived metrics: reproductive activity, relative abundance of YOY, YOY growth rates, adult growth, and adult condition to determine whether we could detect effects of PCBs in the largemouth bass population. These computed metrics, when compared with data sets assembled for numerous largemouth bass populations in North America, provided no evidence of population-level impairment. Results of this study suggest that PCB tissue concentrations associated with effects in laboratory studies do not necessarily translate to detectable effects on largemouth bass populations in their natural environment. [source] Stabilizing effects of extracellular ATP on synaptic efficacy and plasticity in hippocampal pyramidal neuronsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 4 2005Eduardo D. Martín Abstract The role of adenosine triphosphate (ATP) as a neurotransmitter and extracellular diffusible messenger has recently received considerable attention because of its possible participation in the regulation of synaptic plasticity. However, the possible contribution of extracellular ATP in maintaining and regulating synaptic efficacy during intracellular ATP depletion is understudied. We tested the effects of extracellular ATP on excitatory postsynaptic currents (EPSCs) evoked in CA1 pyramidal neurons by Schaffer collateral stimulation. In the absence of intracellular ATP, EPSC rundown was neutralized when a low concentration of ATP (1 µm) was added to the extracellular solution. Adenosine and ATP analogues did not prevent the EPSC rundown. The P2 antagonists piridoxal-5,-phosphate-azophenyl 2,,4,-disulphonate (PPADS) and reactive blue-2, and the P1 adenosine receptor antagonist 8-cyclopentyltheophylline (CPT) had no detectable effects in cells depleted of ATP. However, the protective action of extracellular ATP on synaptic efficacy was blocked by extracellular application of the protein kinase inhibitors K252b and staurosporine. In contrast, K252b and staurosporine per se did not interfere with synaptic transmission in ATP loaded cells. Without intracellular ATP, bath-applied caffeine induced a transient (< 35 min) EPSC potentiation that was transformed into a persistent long-term potentiation (> 80 min) when 1 µm ATP was added extracellularly. An increased probability of transmitter release paralleled the long-term potentiation induced by caffeine, suggesting that it originated presynaptically. Therefore, we conclude that extracellular ATP may operate to maintain and regulate synaptic efficacy and plasticity in conditions of abnormal intracellular ATP depletion by phosphorylation of a surface protein substrate via activation of ecto-protein kinases. [source] Contingent approaches to making likelihood judgments about polychotomous cases: the influence of task factorsJOURNAL OF BEHAVIORAL DECISION MAKING, Issue 4 2005Paul D. Windschitl Abstract Two experiments tested the influence of three task factors on respondents' tendency to use normative, heuristic, and random approaches to making likelihood judgments about polychotomous cases (i.e., cases in which there is more than one alternative to a focal hypothesis). Participants estimated their likelihood of winning hypothetical raffles in which they and other players held various numbers of tickets. Responding on non-numeric scales (vs. numeric ones) and responding under time pressure (vs. self-paced) increased participants' use of a comparison-heuristic approach, resulting in non-normative judgment patterns. A manipulation of evidence representation (whether ticket quantities were represented by numbers or more graphically by bars) did not have reliably detectable effects on processing approaches to likelihood judgment. The authors discuss the implications of these findings for the further development of likelihood judgment theories, and they discuss parallels between contingent processing in choice and contingent processing in likelihood judgment. Copyright © 2005 John Wiley & Sons, Ltd. [source] Experimental infection magnifies inbreeding depression in house miceJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 3 2008P. ILMONEN Abstract It is often assumed that inbreeding reduces resistance to pathogens, yet there are few experimental tests of this idea in vertebrates, and no tests for the effects of moderate levels of inbreeding more commonly found in nature. We mated wild-derived mice with siblings or first cousins and compared the resistance of their offspring to Salmonella infection with outbred controls under laboratory and seminatural conditions. In the laboratory, full-sib inbreeding reduced resistance to Salmonella and survivorship, whereas first-cousin inbreeding had no detectable effects. In competitive population enclosures, we found that first-cousin inbreeding reduced male fitness by 57% in infected vs. only 34% in noninfected control populations. Our study provides experimental evidence that inbreeding reduces resistance and ability to survive pathogenic infection, and moreover, it shows that even moderate inbreeding can cause significant fitness declines under naturalistic conditions of social stress, and especially with exposure to infectious agents. [source] Intrinsic and extrinsic determinants of mountain pine beetle population growthAGRICULTURAL AND FOREST ENTOMOLOGY, Issue 2 2009M. Kurtis Trzcinski Abstract 1,Mountain pine beetle Dendroctonus ponderosae populations have large, economically significant outbreaks. Density dependence and environmental variability are expected to have important effects on their dynamics. We analysed time series data from an outbreak in the 1930s to determine the relative importance of population density and environmental variability on local population growth rates. 2,Resource depletion occurred rapidly at the scale of 0.4 ha and population growth rates were strongly density dependent. Annual environmental changes did not have detectable effects on population growth rates, leading to the conclusion that intrinsic processes influenced local population density more than extrinsic factors during this outbreak. 3,Our calculated value of rmax (1.16) does not suggest intrinsically cyclic population dynamics. Our estimate of rmax and density dependence will be useful in developing applied models of mountain pine beetle outbreaks, and the subsequent evaluation of management strategies. [source] Cesium-133: A potential reporter of the hepatic uptake of contrast agentsMAGNETIC RESONANCE IN MEDICINE, Issue 4 2001Jean-Marie Colet Abstract NMR spectroscopy of intracellularly located 133Cs has been used to monitor the uptake of Gd-EOB-DTPA by the isolated rat liver. As shown by 31P spectroscopy, accumulation of 133Cs ions in hepatocytes does not produce detectable effects on the metabolism. The hepatic internalization of Gd-EOB-DTPA was followed by the paramagnetic relaxation enhancement of the intracellular 133Cs ions, and confirmed by parallel quantitations of Gd and Cs run by inductively coupled plasma (ICP) analysis of liver samples and aliquots of perfusate. The relaxation data significantly underestimate the Gd content, suggesting a potential compartmentation of Cs+ and/or the contrast agent. Magn Reson Med 45:711,715, 2001. © 2001 Wiley-Liss, Inc. [source] Stability of ecosystem properties in response to above-ground functional group richness and compositionOIKOS, Issue 1 2000David A. Wardle While there has been a rapidly increasing research effort focused on understanding whether and how composition and richness of species and functional groups may determine ecosystem properties, much remains unknown about how these community attributes affect the dynamic properties of ecosystems. We conducted an experiment in 540 mini-ecosystems in glasshouse conditions, using an experimental design previously shown to be appropriate for testing for functional group richness and composition effects in ecosystems. Artificial communities representing 12 different above-ground community structures were assembled. These included treatments consisting of monoculture and two- and four-species mixtures from a pool of four plant species; each plant species represented a different functional group. Additional treatments included two herbivore species, either singly or in mixture, and with or without top predators. These experimental units were then either subjected to an experimentally imposed disturbance (drought) for 40 d or left undisturbed. Community composition and drought both had important effects on plant productivity and biomass, and on several below-ground chemical and biological properties, including those linked to the functioning of the decomposer subsystem. Many of these compositional effects were due to effects both of plant and of herbivore species. Plant functional group richness also exerted positive effects on plant biomass and productivity, but not on any of the below-ground properties. Above-ground composition also had important effects on the response of below-ground properties to drought and thus influenced ecosystem stability (resistance); effects of composition on drought resistance of above-ground plant response variables and soil chemical properties were weaker and less consistent. Despite the positive effects of plant functional group richness on some ecosystem properties, there was no effect of richness on the resistance of any of the ecosystem properties we considered. Although herbivores had detectable effects on the resistance of some ecosystem properties, there were no effects of the mixed herbivore species treatment on resistance relative to the single species herbivore treatments. Increasing above-ground food chain length from zero to three trophic levels did not have any consistent effect on the stability of ecosystem properties. There was no evidence of either above-ground composition or functional group richness affecting the recovery rate of ecosystem properties from drought and hence ecosystem resilience. Our data collectively point to the role of composition (identity of functional group), but not functional group richness, in determining the stability (resistance to disturbance) of ecosystem properties, and indicates that the nature of the above-ground community can be an important determinant of the consistency of delivery of ecosystem services. [source] Persistent Advantage or Disadvantage?: Evidence in Support of the Intergenerational Drag HypothesisAMERICAN JOURNAL OF ECONOMICS AND SOCIOLOGY, Issue 2 2001William Darity By utilizing the Integrated Public Use Microdata Series (IPUMS) and a measure of occupational prestige (OCCSCORE) as a labor market outcome, the authors examine variations in the degree of labor market discrimination faced by several ethnic and racial groups in the United States between 1880 and 1990. Results demonstrate that the sharpest decline in labor market discrimination against blacks occurred between 1960 and 1980. For black males the extent of labor market discrimination was greater in all census years in IPUMS after 1880 until 1970, evidence contradicting the conventional expectation that market-based discrimination will decline progressively over time by dint of competitive pressure. Finally, after replicating George Borjas' "ethnic capital" exercise, the authors pool the 1880, 1900, and 1910 data to determine the relative magnitude of a group's gains and losses in occupational prestige due to group advantage or disadvantage in human capital endowments and due to favorable or unfavorable treatment (nepotism or discrimination) of those endowments in the labor market. The authors then examine statistically whether the group human capital advantage or disadvantage and group exposure to nepotism or discrimination at the turn of the century affects labor market outcomes for their descendants today. Results indicate strong effects of the past on present labor market outcomes. Hence, the essence of the study is the statistical demonstration that there are significant and detectable effects on current generations of the labor market experiences of their racial/ethnic ancestors. [source] |