67 resultados para Plants, Effect of X-rays on
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In the temperate zone, food availability and winter weather place serious constraints on European Barn Owl Tyto alba populations. Using data collected over 22years in a Swiss population, we analysed the influence of early pre-breeding food conditions and winter severity on between-year variations in population size and reproductive performance. To estimate pre-breeding food conditions, we attempted a novel approach based on an index that combines Tawny Owl Strix aluco reproductive parameters and the occurrence of wood mice Apodemus sp. in their diet. Tawny Owls breed earlier in the season than Barn Owls and are strongly dependent on the abundance of wood mice for breeding. This index was strongly positively associated with the number of breeding pairs and early breeding in the Barn Owl. Winter severity, measured by snow cover and low temperatures, had a pronounced negative influence on the size of the breeding population and clutch size. Food conditions early in the breeding season and winter severity differentially affect the Barn Owl life cycle. We were able to use aspects of the ecology and demography of the Tawny Owl as an indicator of the quality of the environment for a related species of similar ecology, in this case the Barn Owl.
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To assess the effect of weight loss on resting metabolic rate (RMR), the energy expenditure of eight obese prepubertal children (age 9 +/- 1 years; weight 48.7 +/- 9.1 kg; BMI 25.3 +/- 3.9) and of 14 age-matched children of normal body weight (age 9 +/- 1 years; weight 28.8 +/- 5.6 kg; BMI 16.5 +/- 1.7) was measured by indirect calorimetry. The obese children were reinvestigated after a mean weight loss of 5.4 +/- 1.2 kg induced by a six-months mixed hypocaloric diet. Before slimming, the obese group showed a higher daily energy intake than the control group (10.40 +/- 3.45 MJ/day vs 7.97 +/- 2.02 MJ/day respectively; P less than 0.05) but a similar value was observed per unit fat-free mass (FFM) (0.315 +/- 0.032 MJ/kgFFM/day vs 0.329 +/- 0.041 MJ/kgFFM/day respectively). The average RMR of the obese children was greater than that of the control group (5217 +/- 531 kJ/day vs 4477 +/- 506 kJ/day) but similar after adjusting for FFM (4728 +/- 3102 kJ/day vs 4899 +/- 3102 kJ/day). Weight loss resulted in a reduction in RMR (5217 +/- 531 kJ/day vs 4874 +/- 820 kJ/day), each kg of weight loss being accompanied by a decrease of RMR of 64 kJ (15.3 kcal) per day. The changes in RMR induced by weight loss paralleled the changes in FFM. No difference was found in average RQ in obese children vs controls (0.85 +/- 0.03 vs 0.87 +/- 0.03 respectively) and in the obese children before and after weight loss (0.87 +/- 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)
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We modeled work performance as outcomes of individual-differences mediated by technical performance. Beyond the "usual suspects" (e.g., general mental ability, and personality), we also measured the ethical development of participants (n = 460). We surmised that ethical development - which has not been extensively studied as a predictor of work performance while controlling for established predictors - captures unique variance in both technical and work performance. Results demonstrated incremental validity for ethical development in predicting technical performance, which in turn predicted work performance. The indirect effect of ethical development was significant too. Our results highlight the importance of process models of performance, which include proximal as well as distal individual differences.
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Introduction: Infection with Epstein-Barr Virus (EBV) and a lack invitamin D are emerging as the twomost significant environmental triggersof multiple sclerosis (MS). Sincewe and others have shown that CD8+T cells are important immune mediatorsof the inflammatory response inMS, we examined whether vitamin Ddirectly affects the CD8+ T cell response.We also explored if vitaminDmodulates the EBV-specific CD8+ Tcell response. Methods: PBMC of 10patients with early MS and 10 healthycontrols (HC) were stimulated eitherwith a pool of EBVimmunodominantpeptides or anti-CD3/anti-CD28 beads.Cytokine secretion was assessed witha Cytometric Beads Array (CBA),ELISA and intracellular cytokinestaining. To examine whether vitaminD could directly modulate CD8+ Tcell immune responses, we depletedCD4+ T cells using a negative selection.Results: We found that vitaminD-treated PBMC stimulated eitherwith the EBV peptide pool or anti-CD3/anti-CD28 beads adopted ananti-inflammatory profile: significantdecrease in IFN-and TNF secretion,contrasting with a significant increasein IL-5 and TGF-secretion. At baseline,but also after vitamin D stimulation,IL-5 was significantly less producedby stimulated CD8+ T cells ofearly MS than HC. Finally, using depletionof CD4+ T cells, we couldshow that vitaminDcan directlymodulateCD8+ T cells. Discussion: Ourdata suggest that vitaminDconfers ananti-inflammatory profile to CD8+ Tcells, without the help of CD4+ Tcells. Even if vitamin D has a significanteffect on CD8+ T cells of earlyMS patients, this "rescuing" effect isof smaller magnitude than in HC subjects.Finally, vitamin D does influencethe CD8+ T cell response toEBV in early MS patients, suggestingthat there is an interplay betweenthese two major environmental factorsof MS.
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The effect of abscisic acid (ABA) on the growth of maize roots maintained in the dark is investigated in relation to the root varieties and the root age, the mode of application, the concentration used and the duration of both the treatment and the culture. In all the assays, when ABA produces a significant change in root elongation, it shows an inhibitory effect which is enhanced with increasing ABA concentration. The data strongly support the hypothesis that ABA could be one of the growth inhibitors which are formed in or released from the root cap.
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Among 645 obese patients examined at an out-patient clinic for obese patients by physical examination and a computerized questionnaire, two subgroups of patients could be identified according to their nutritional preferences: 177 patients preferred carbohydrates exclusively (group A) and 73 patients fat exclusively (group B). No definite preferences were formulated by the other patients. Among patients under 25 years, only 3 belonged to group B and 49 to group A, while in older patients no significant differences were found. Among patients with BMI less than 30, there were significantly fewer patients from group B than from group A (p = 0.006), while in patients with BMI greater than 30 no significant difference was observed. There were significantly more men in group B than in group A. 57% of the patients of group B complained of physical symptoms related to their obesity, compared to 37% in group A (p = 0.006). 26% of group B suffered from joints and muscles compared to 13% of group A (p = 0.003). Hyperglycemia (greater than 5,6 mmol/l) was found in 21% of group A and in 40% of group B (p less than 0.005). Hypercholesterolemia (greater than 6.5 mmol/l) was found in 20% of group A and in 32% of group B (p less than 0.05). In conclusion, obese patients who prefer fat have more general symptoms related to obesity, more abnormal physical signs, and more frequently have hyperglycemia and hypercholesterolemia than patients who prefer carbohydrates.
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OBJECTIVES: The inoculum effect (IE) is an increase in the minimum inhibitory concentration (MIC) at high bacterial densities. The effect of three inoculum sizes on the selection of resistance to vancomycin, daptomycin, and linezolid was investigated in methicillin-resistant Staphylococcus aureus (MRSA). METHODS: Low (10(4) CFU/ml), medium (10(6) CFU/ml), and high (10(8) CFU/ml) inocula of MRSA were exposed to twofold increasing concentrations of either drug during 15 days of cycling. MICs for low (MICL), medium (MICM), and high (MICH) inocula were determined daily. Conventional MICs were measured at days 1, 5, 10, and 15. Experiments were performed in triplicate. RESULTS: At the beginning of the experiment a small IE was observed for vancomycin (MICL=1 μg/ml, MICM=1-2 μg/ml, and MICH=2 μg/ml) and a significant IE for daptomycin (MICL=0.25 μg/ml, MICM=0.25-0.5 μg/ml, and MICH=2 μg/ml). Linezolid exhibited no IE at low and medium inocula (MICL=1 μg/ml and MICM=1-2 μg/ml), but with the high inoculum, concentrations up to 2,048 μg/ml did not fully inhibit visual growth. During cycling, increase of MIC was observed for all antibiotics. At day 15, MICL, MICM, and MICH of vancomycin were 2-4, 4-8, and 4-16 μg/ml and of daptomycin were 0.5-2, 8-128, and 64-256 μg/ml, respectively. MICL and MICM of linezolid were 1 and 2-4 μg/ml, respectively. Conventional MICs showed vancomycin and daptomycin selection of resistance since day 5 depending on the inocula. No selection of linezolid resistance was observed. CONCLUSIONS: Our results showed the importance of the inoculum size in the development of resistance. Measures aimed at lowering the inoculum at the site of infection should be used whenever possible in parallel to antimicrobial therapy.
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Manganese (Mn(2+))-enhanced magnetic resonance imaging studies of the neuronal pathways of the hypothalamus showed that information about the regulation of food intake and energy balance circulate through specific hypothalamic nuclei. The dehydration-induced anorexia (DIA) model demonstrated to be appropriate for studying the hypothalamus with Mn(2+)-enhanced magnetic resonance imaging. Manganese is involved in the normal functioning of a variety of physiological processes and is associated with enzymes contributing to neurotransmitter synthesis and metabolism. It also induces psychiatric and motor disturbances. The molecular mechanisms by which Mn(2+) produces alterations of the hypothalamic physiological processes are not well understood. (1)H-magnetic resonance spectroscopy measurements of the rodent hypothalamus are challenging due to the distant location of the hypothalamus resulting in limited measurement sensitivity. The present study proposed to investigate the effects of Mn(2+) on the neurochemical profile of the hypothalamus in normal, DIA, and overnight fasted female rats at 14.1 T. Results provide evidence that γ-aminobutyric acid has an essential role in the maintenance of energy homeostasis in the hypothalamus but is not condition specific. On the contrary, glutamine, glutamate, and taurine appear to respond more accurately to Mn(2+) exposure. An increase in glutamine levels could also be a characteristic response of the hypothalamus to DIA.
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Using numerical simulations we investigated the effect of DNA supercoiling on the topological equilibrium of DNA molecules. We showed that under the steady state conditions that maintain the same effective deficit of the linking number in unknotted and knotted DNA molecules the topological equilibrium results in a much smaller fraction of knots than in the case of torsionally relaxed DNA molecules. Based on these results we propose that one of the important functions of DNA supercoiling is to reduce formation of DNA knots.
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Background: Numerous studies have shown a negative association between birth weight (BW) and blood pressure (BP) later in life. To estimate the direct effect of BW on BP, it is conventional to condition on current weight (CW). However, such conditioning can induce collider stratification bias in the estimate of the direct effect. Objective: To bound the potential bias due to U, an unmeasured common cause of CW and BP, on the estimate of the (controlled) direct effect of BW on BP. Methods: Data from a school based study in Switzerland were used (N = 4,005; 2,010 B/1,995 G; mean age: 12.3 yr [range: 10.1-14.9]). Measured common causes of BW-BP (SES, smoking, body weight, and hypertension status of the mother) and CW-BP (breastfeeding and child's physical activity and diet) were identified with DAGs. Linear regression models were fitted to estimate the association between BW and BP. Sensitivity analyses were conducted to assess the potential effect of U on the association between BW and BP. U was assumed 1) to be a binary variable that affected BP by the same magnitude in low BWand in normal BW children and 2) to have a different prevalence in low BW children and in normal BW children for a given CW. Results: A small negative association was observed between BW and BP [beta: -0.3 mmHg/kg (95% CI: -0.9 to 0.3)]. The association was strengthened upon conditioning for CW [beta: -1.5 mmHg/kg (95% CI: -2.1 to -0.9)]. Upon further conditioning on common causes of BW-BP and CW-BP, the association did not change substantially [beta: -1.4 mmHg/kg (95% CI: -2.0 to -0.8)]. The negative association could be explained by U only if U was strongly associated with BP and if there was a large difference in the prevalence of U between low BWand normal BW children. Conclusion: The observed negative association between BW and BP upon adjustment for CW was not easily explained by an unmeasured common cause of CWand BP.
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PURPOSE: The present study was designed to determine the stimulation intensity necessary for an adequate assessment of central and peripheral components of neuromuscular fatigue of the knee extensors. METHODS: Three different stimulation intensities (100, 120 and 150 % of the lowest intensity evoking a plateau in M-waves and twitch amplitudes, optimal stimulation intensity, OSI) were used to assess voluntary activation level (VAL) as well as M-wave, twitch and doublet amplitudes before, during and after an incremental isometric exercise performed by 14 (8 men) healthy and physically active volunteers. A visual analog scale was used to evaluate the associated discomfort. RESULTS: There was no difference (p > 0.05) in VAL between the three intensities before and after exercise. However, we found that stimulating at 100 % OSI may overestimate the extent of peripheral fatigue during exercise, whereas 150 % OSI stimulations led to greater discomfort associated with doublet stimulations as well as to an increased antagonist co-activation compared to 100 % OSI. CONCLUSION: We recommend using 120 % OSI, as it constitutes a good trade-off between discomfort and reliable measurements.
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The ability to identify letters and encode their position is a crucial step of the word recognition process. However and despite their word identification problem, the ability of dyslexic children to encode letter identity and letter-position within strings was not systematically investigated. This study aimed at filling this gap and further explored how letter identity and letter-position encoding is modulated by letter context in developmental dyslexia. For this purpose, a letter-string comparison task was administered to French dyslexic children and two chronological age (CA) and reading age (RA)-matched control groups. Children had to judge whether two successively and briefly presented four-letter strings were identical or different. Letter-position and letter identity were manipulated through the transposition (e.g., RTGM vs. RMGT) or substitution of two letters (e.g., TSHF vs. TGHD). Non-words, pseudo-words, and words were used as stimuli to investigate sub-lexical and lexical effects on letter encoding. Dyslexic children showed both substitution and transposition detection problems relative to CA-controls. A substitution advantage over transpositions was only found for words in dyslexic children whereas it extended to pseudo-words in RA-controls and to all type of items in CA-controls. Letters were better identified in the dyslexic group when belonging to orthographically familiar strings. Letter-position encoding was very impaired in dyslexic children who did not show any word context effect in contrast to CA-controls. Overall, the current findings point to a strong letter identity and letter-position encoding disorder in developmental dyslexia.
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BACKGROUND: Innate immune sensors control key cytokines that regulate T-cell priming and T-cell fate. This is particularly evident in allergic reactions, which represent ideal systems to study the interplay of innate and adaptive immunity. In patients with contact dermatitis, inflammasome-mediated IL-1 activation is responsible for a TH1 immune response. Surprisingly, the IL-1 signaling pathway was also proposed to control the activation of thymic stromal lymphopoietin (TSLP), a cytokine implicated in development of the TH2 response in patients with atopic dermatitis (AD) and asthma. OBJECTIVES: We sought to assess the effect of the inflammasome on TSLP expression levels and the development of AD. METHODS: We studied the effect of the inflammasome activator 2,4-dinitrofluorobenzene, and IL-1β on TSLP mRNA expression levels in mouse and human cell lines (in vitro assays), as well as in live mice and on human skin transplants. We also assessed the effect of 2,4-dinitrofluorobenzene on TSLP and the TH2 response in mice in which the inflammasome and IL-1 signaling pathways were blocked, either genetically or pharmacologically, in 2 models of AD. RESULTS: We provide in vitro and in vivo evidence that inflammasome activation has an inhibitory role on TSLP mRNA expression and TH2 cell fate in the skin. We also show that solvents influence the activation of TSLP and IL-1β and direct the T-cell fate to a given hapten. CONCLUSION: Our observations strongly suggest that the TH1 versus TH2 cell fate decision is regulated at multiple levels and starts with innate immune events occurring within peripheral epithelial tissues.
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Primary roots of intact maize seedlings (cv. LG11) were pretreated when kept vertically (1 or 2 in the dark) with a droplet of buffer solution containing ABA (at different concentrations) applied to the root tip. Then, apical root segments were prepared and placed horizontally in both light and darkness. The downward curvature was measured. In the light, curvature was greater than in darkness and ABA (5×10−5 mol·dm−3) significantly enhanced the curvature in both darkness and light. The amplitude of the increase in the gravireaction was found to be dependent on the ABA concentration and the duration of the pretreatment.