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See detailNitrogen dynamics in Posidonia oceanica cuttings: implications for transplantation experiments
Lepoint, Gilles ULg; Vangeluwe, Denis; Eisinger, Michael et al

in Marine Pollution Bulletin (2004), 48(5-6), 465-470

A N-15 tracer study was performed during an experimental transplantation trial of natural Posidonia oceanica cuttings. The experiment was done in situ at 17 m depth in the Revellata Bay (Calvi, NW Corsica ... [more ▼]

A N-15 tracer study was performed during an experimental transplantation trial of natural Posidonia oceanica cuttings. The experiment was done in situ at 17 m depth in the Revellata Bay (Calvi, NW Corsica, France). Despite high survival rates of transplants (>90%) after one year, the weight and the N content of transplants are significantly lower than those of reference plants. In absence of roots, the transplants are not able to meet their N requirement because, leaf uptake is insufficient to replenish the N lost during the natural leaf decay. This could constitute a major cause of long-term failure for transplantation experiments or natural recolonisation processes. The increase of the N-15 content in the roots shows that the plant re-allocates the nitrogen of one organ (i.e. leaves, rhizomes) to ensure the growth of another (i.e. roots). (C) 2003 Elsevier Ltd. All rights reserved. [less ▲]

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See detailNitrogen enrichment, boron depletion and magnetic fields in slowly-rotating B-type dwarfs
Morel, Thierry ULg; Hubrig, S.; Briquet, Maryline ULg

in Astronomy and Astrophysics (2008), 481

Evolutionary models for massive stars, accounting for rotational mixing effects, do not predict any core-processed material at the surface of B dwarfs with low rotational velocities. Contrary to ... [more ▼]

Evolutionary models for massive stars, accounting for rotational mixing effects, do not predict any core-processed material at the surface of B dwarfs with low rotational velocities. Contrary to theoretical expectations, we present a detailed and fully-homogeneous, NLTE abundance analysis of 20 early B-type dwarfs and (sub)giants that reveals the existence of a population of nitrogen-rich and boron-depleted, yet intrinsically slowly-rotating objects. The low-rotation rate of several of these stars is firmly established, either from the occurrence of phase-locked UV wind line-profile variations, which can be ascribed to rotational modulation, or from theoretical modelling in the pulsating variables. The observational data presently available suggest a higher incidence of chemical peculiarities in stars with a (weak) detected magnetic field. This opens the possibility that magnetic phenomena are important in altering the photospheric abundances of early B dwarfs, even for surface field strengths at the one hundred Gauss level. However, further spectropolarimetric observations are needed to assess the validity of this hypothesis. [less ▲]

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See detailNitrogen excess in slowly-rotating beta Cephei stars: deep mixing or diffusion?
Morel, Thierry ULg; Butler, K.; Aerts, C. et al

in Communications in Asteroseismology (2007), 150

We present the results of an NLTE abundance study of a small sample of β Cephei stars, which point to the existence of a population of slowly-rotating B-type pulsators exhibiting a significant amount of ... [more ▼]

We present the results of an NLTE abundance study of a small sample of β Cephei stars, which point to the existence of a population of slowly-rotating B-type pulsators exhibiting a significant amount of nitrogen-enriched material at their surface. Although the origin of this nitrogen excess remains unclear, an overabundance preferentially occurring in stars with a detected magnetic field seems to emerge at this stage. Full details can be found in Morel et al. (2006). [less ▲]

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See detailNitrogen excretions in dairy cows on a rotational grazing system: effects of fertilization type, days in the paddock and time period.
Dufrasne, Isabelle ULg; Robaye, Vincent ULg; Istasse, Louis ULg et al

in Schnyder, Hans; Isselstein, J.; Taube, F. (Eds.) et al Grassland in a changing world (2010, September)

The present study aims to quantify nitrogen (N) excretions in dairy cows on a rotational grazing system with different types of fertilization (mineral N, slurry and compost) after 3 or 5 days in the ... [more ▼]

The present study aims to quantify nitrogen (N) excretions in dairy cows on a rotational grazing system with different types of fertilization (mineral N, slurry and compost) after 3 or 5 days in the paddock and during two different periods in June and September. Individual samples of faeces and urine were collected to assess N excretions from cows in the paddocks. The urea content in milk from the tank or from the individual cows was also measured. N intake was higher on day 3 compared to day 5 (465 vs 425 g d-1, P<0.001) and in September as compared to June (488 vs 425 g d-1, P<0.001) but was not influenced by the fertilization type. The amount of excreted urinary N was significantly higher in the mineral N group than in the two other groups (272 vs 226 g d-1; P<0.001). The N excretion in faeces and urines decreased with days (92 vs 84 g d-1, P<0.01; 256 vs 228 g d-1, P<0.001 respectively for days 3 and 5). Urinary N excretion was lower in June than in September (181 vs 302 g d-1, P<0.001) while the N excretion in the faeces was higher (96 vs 80 g d-1, P<0.01). [less ▲]

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See detailNitrogen flaring stages of novae
Swings, Polydore ULg

in Publications of the American Astronomical Society (1946)

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See detailThe nitrogen isotope ratio in a few Oort Cloud comets
Jehin, Emmanuel ULg; Arpigny, Claude ULg; Manfroid, Jean ULg et al

in 35th COSPAR Scientific Assembly (2004)

In the past few years, high-resolution (R ˜ 70,000) and high quality spectra of the CN B^2Sigma^+ - X^2Sigma^+ (0,0) band (at 388 nm) of several Oort Could comets have been collected by our team in ... [more ▼]

In the past few years, high-resolution (R ˜ 70,000) and high quality spectra of the CN B^2Sigma^+ - X^2Sigma^+ (0,0) band (at 388 nm) of several Oort Could comets have been collected by our team in different observatories and have allowed the first optical detections of [SUP]12[/SUP]C[SUP]15[/SUP]N. Observations with first class spectrographs on large 8m telescopes, such as UVES at the ESO VLT, have shown that such very efficient equipment are able to provide isotopic ratios for comets as faint as m_r ˜ 9 (heliocentric magnitude), opening up the possibility of carrying out a systematic analysis over a significant sample of comets. While the measured [SUP]12[/SUP]C/[SUP]13[/SUP]C isotope ratios in the different comets are in good agreement with the Solar system value (89), the derived [SUP]14[/SUP]N/[SUP]15[/SUP]N ratios are only about half the value in Earth's atmosphere (272), indicating an excess of [SUP]15[/SUP]N by a factor of about 2 with respect to the "cosmic" value. It is striking to note that the optical determinations of [SUP]14[/SUP]N/[SUP]15[/SUP]N in the different comets are consistent with each other (140 � 30), but not with the ratios derived for comet Hale-Bopp from sub-millimeter measurements on HCN, generally believed to be the main parent of CN. This discrepancy could indicate the existence of (an) other unknown parent(s) of CN, with an even higher [SUP]15[/SUP]N excess. Organic compounds like those found in interplanetary dust particles (IDPs) are good candidates. Further determinations from HCN are now badly needed in other comets. Obtaining the value of the N isotopic ratio in Jupiter-family short-period comets would be of great significance in view of their presumed different place of birth. Much is also expected in this respect, as in many others, from several space missions such as Deep Impact, Stardust, and Rosetta. [less ▲]

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See detailNitrogen Isotope Ratios in Comets. ESO Astrophysics Symposia
Cochran, Anita L; Jehin, Emmanuel ULg; Manfroid, Jean ULg et al

in Precision Spectroscopy in Astrophysics (2008)

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See detailNitrogen K-shell photoabsorption
Garcia, J; Kallman, T R; Witthoeft, M et al

in Astrophysical Journal Supplement Series (2009), 185

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See detailNitrogen leaching forecasting: modelling and measurements
Sohier, Catherine ULg; Vandenberghe, Christophe ULg; Dautrebande, Sylvia et al

in Bruthans, Jiri; Kovar, Karel; Hrkal, Zbynek (Eds.) International Interdisciplinary Conference on Predictions for Hydrology, Ecology and water Resources Management Using Data And Models To Benefit Society (2008)

European nitrate directive (CEE/91/676) imposes wide monitoring of Nitrogen in farmlands. The Walloon Region (South of Belgium – 750 000 ha of arable land) develops an original combination of methods to ... [more ▼]

European nitrate directive (CEE/91/676) imposes wide monitoring of Nitrogen in farmlands. The Walloon Region (South of Belgium – 750 000 ha of arable land) develops an original combination of methods to reach European objectives in this topic. On the one hand, water and nitrogen flows and balances are modelled, on the other hand, an Agricultural Surface Survey is put into practice to monitor nitrate nitrogen in the soil at the beginning of the leaching period. The Agricultural Surface Survey is constituted by a 30 reference farms network within more than 200 plots are monitored each in order to fix annual standards for nitrate profiles. Each year, about 1% of the Walloon farms are assessed about their good nitrogen management. Thanks to the existence of a useful database of nitrate profiles measured through six years in the whole Walloon Region, validation of the simulations in the vadose zone can be realised. The comparison of the measured data and the simulation shows a good accuracy of the EPICgrid model. [less ▲]

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See detailNitrogen-containing bisphosphonates can inhibit angiogenesis in vivo without the involvement of farnesyl pyrophosphate synthase.
Stresing, Verena; Fournier, Pierrick G; Bellahcene, Akeila ULg et al

in Bone (2011), 48(2), 259-66

Nitrogen-containing bisphosphonates (N-BPs) are widely used to block bone destruction associated with bone metastasis because they are effective inhibitors of osteoclast-mediated bone resorption. More ... [more ▼]

Nitrogen-containing bisphosphonates (N-BPs) are widely used to block bone destruction associated with bone metastasis because they are effective inhibitors of osteoclast-mediated bone resorption. More specifically, once internalized by osteoclasts, N-BPs block the activity of farnesyl pyrophosphate synthase (FPPS), a key enzyme in the mevalonate pathway. In addition to their antiresorptive activity, preclinical evidence shows that N-BPs have antiangiogenic properties. However, the exact reasons for which N-BPs inhibit angiogenesis remain largely unknown. Using different angiogenesis models, we examined here the effects of zoledronate, risedronate and three structural analogs of risedronate (NE-58025, NE-58051 and NE-10790) with lower potencies to inhibit FPPS activity. Risedronate and zoledronate were much more potent than NE-compounds at inhibiting both endothelial cell proliferation in vitro and vessel sprouting in the chicken egg chorioallantoic membrane (CAM) assay. In addition, only risedronate and zoledronate inhibited the revascularization of the prostate gland in testosterone-stimulated castrated rats. Moreover, as opposed to NE-compounds, risedronate and zoledronate induced intracellular accumulation of isopentenyl pyrophosphate (IPP) in endothelial cells by blocking the activity of the IPP-consuming enzyme FPPS. Thus, these results indicated that N-BPs inhibited angiogenesis in a FPPS-dependent manner. However, drug concentrations used to inhibit angiogenesis, both in vitro and in the CAM and prostate gland assays, were high. In contrast, a low concentration of risedronate (1 muM) was sufficient to inhibit blood vessel formation in the ex vivo rat aortic ring assay. Moreover, NE-58025 (which had a 7-fold lower potency than risedronate to inhibit FPPS activity) was as effective as risedronate to reduce angiogenesis in the rat aortic ring assay. In conclusion, our results suggest that low concentrations of N-BPs inhibit angiogenesis in a FPPS-independent manner, whereas higher drug concentrations were required to inhibit FPPS activity in vivo. [less ▲]

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See detailNITROGEN-RICH METAMORPHIC FLUIDS IN DEVONIAN METASEDIMENTS FROM BASTOGNE, BELGIUM
Darimont, Anne ULg; BURKE, E.; TOURET, J.

in Bulletin de Minéralogie (1988), 111(3-4), 321-330

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See detailNitroglycerin sensitises in healthy subjects CNS structures involved in migraine pathophysiology: evidence from a study of nociceptive blink reflexes and visual evoked potentials.
Di Clemente, Laura; Coppola, Gianluca; Magis, Delphine ULg et al

in Pain (2009), 144(1-2), 156-61

Nitroglycerin (NTG), a NO donor, induces an attack in migraine patients approximately 4-6 h after administration. The causative mechanisms are not known, but the long delay leaves room for a central ... [more ▼]

Nitroglycerin (NTG), a NO donor, induces an attack in migraine patients approximately 4-6 h after administration. The causative mechanisms are not known, but the long delay leaves room for a central effect, such as a change in neuronal excitability and synaptic transmission of various CNS areas involved in pain and behaviour including trigeminal nucleus caudalis and monoaminergic brain stem nuclei. To explore the central action of NTG, we have studied its effects on amplitude and habituation of the nociceptive blink reflex (nBR) and the visual evoked potential (VEP) before, 1 h and 4 h after administration of NTG (1.2 mg sublingual) or placebo (vehicle sublingual) in two groups of 10 healthy volunteers. We found a significant decrease in nBR pain and reflex thresholds both 1 and 4 h post-NTG. At the 4 h time point R2 latency was shorter (p=0.04) and R2 response area increased (p<0.01) after NTG but not after placebo. Habituation tended to become more pronounced after both NTG and placebo administration. There was a significant amplitude increase in the 5th VEP block (p=0.03) at 1h after NTG and in the 1st block (p=0.04) at 4 h. VEP habituation was replaced by potentiation at both delays after NTG; the change in habituation slope was significant at 1h (p=0.02). There were no significant VEP changes in subjects who received sublingual placebo. In conclusion, we found that in healthy subjects sublingual NTG, but not its vehicle, induces changes in a trigeminal nociceptive reflex and an evoked cortical response which are comparable to those found immediately before and during an attack of migraine. These changes could be relevant for the attack-triggering effect of NTG in migraineurs. [less ▲]

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See detailNitroglycerin-induced nNOS increase in rat trigeminal nucleus caudalis is inhibited by systemic administration of lysine acetylsalicylate but not of sumatriptan
Pardutz, A.; Szatmari, E.; Vecsei, L. et al

in Cephalalgia : An International Journal of Headache (2004), 24(6), 439-445

Systemic administration of nitroglycerin (NTG), a nitric oxide (NO) donor, in migraineurs triggers after several hours an attack of which the precise mechanisms are unknown. We found previously in rats ... [more ▼]

Systemic administration of nitroglycerin (NTG), a nitric oxide (NO) donor, in migraineurs triggers after several hours an attack of which the precise mechanisms are unknown. We found previously in rats that nitroglycerin (10 mg/kg s.c.) is able to increase significantly after 4 h the number of neuronal nitric oxide synthase (nNOS)-immunoreactive neurones in the cervical part of trigeminal nucleus caudalis. In the present experiments, we demonstrate that the 5-HT1(B/D) agonist sumatriptan (0.6 mg/kg s.c.) does not alter this phenomenon when given before NTG. By contrast, pretreatment with lysine acetylsalicylate (50 mg/kg i.m.) attenuates the NTG-induced nNOS expression in the superficial laminae of trigeminal nucleus caudalis. These findings suggest that effect of NTG on nNOS at a high dosage may involve the cycloxygenase pathway and that activation of the peripheral 5-HT1(B/D) receptors is not able to modify this effect. These data could help to better understand the role of NO in the pathogenesis of headaches and the action of antimigraine drugs. [less ▲]

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See detailNitrosomonas europaea-like bacteria detected as the dominant beta-subclass Proteobacteria ammonia oxidisers in reference and limed acid forest soils
Carnol, Monique ULg; Kowalchuk, G. A.; De Boer, W.

in Soil Biology & Biochemistry (2002), 34

Net nitrification in intact soil cores and the community of ammonia-oxidising bacteria were studied in acid Norway spruce (Picea abies (L.) Karst) and sessile oak (Quercus petraea (Matt. Lieb.)) soils ... [more ▼]

Net nitrification in intact soil cores and the community of ammonia-oxidising bacteria were studied in acid Norway spruce (Picea abies (L.) Karst) and sessile oak (Quercus petraea (Matt. Lieb.)) soils (Haute Ardenne, east Belgium) 18 months after treatment with 5 t ha(-1) dolomite lime. Liming caused a significant increase in nitrification in the upper soil layers (0.15 m) of both stands. DGGE (denaturing gradient gel electrophoresis) profiling after P-subclass ammonia oxidiser-specific polymerase chain reaction (PCR), combined with hybridisation and sequencing of excised DGGE bands revealed a dominance of Nitrosomonas europaea-like sequences, independent of soil horizon, tree species and lime treatment. A minority Nitrosospira-like population was detected, which showed affinity to nitrosospiras previously detected in acid soil. These results contrast with several reports suggesting a dominance of Nitrosospira-like organisms among ammonia oxidiser communities in acid soils. (C) 2002 Elsevier Science Ltd. All rights reserved. [less ▲]

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See detailNitrous oxide and xenon prevent amphetamine-induced carrier-mediated dopamine release in a memantine-like fashion and protect against behavioral sensitization
David, Hélène N.; Ansseau, Marc ULg; Lemaire, Michelle ULg et al

in Biological Psychiatry (2006), 60(1), 49-57

Background. Amphetamine administration induces stimulation-independent dopainine release in the nucleus accumbens (NAcc) through reverse dopamine transport, a critical neurochemical event involved in its ... [more ▼]

Background. Amphetamine administration induces stimulation-independent dopainine release in the nucleus accumbens (NAcc) through reverse dopamine transport, a critical neurochemical event involved in its psycbostimulant action, and, furthermore decreases stimulation-dependent vesicular dopamine release. These effects may involve possible indirect glutamateigic mechanisms. Methods: We investigated the effiects of nitrous oxide and xenon, which possess antagonistic action at the N-methyl-D-aspartate (NMDA) receptor, on brain slices ex vivo on aniphetamine-induced changes in carrier-mediated and KCI-evoked dopamine release in the NAcc, and in vivo on ampbetamine-induced locomotor sensitization Results: Like the low-affininity NMDA receptor antagonist memantine, but not the prototypical compound MK-801, nitrous oxide and xenon at appropriate concentrations blocked both the increase in carrier-mediated dopamine release and locomotor sensitization produced by amphetamine. Conclusions: In contrast to what has generally been found using prototypical NMDA receptor antagonists, these data regarding the effect qf memantine, nitrous oxide, and xenon support the hypothesis that activation qf certain NMDA receptors (possibly those qf containing the NR1a/NR2D subunit) in the NAcc is involved in the ampbetamine-induced increase in carrier-mediated dopamine release and the development qf behavioral sensitization to amphetamine. Nitrous oxide, xenon, and memantine may be of therapeutic interest for treating drug dependence. [less ▲]

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