216 research outputs found
Aerosol deposition and origin in French mountains estimated with soil inventories of 210Pb and artificial radionuclides
No full textRadionuclide inventories were measured in soils from different French mountainous areas: Chaîne des Puys (Massif Central), Eastern Corsica, Jura, Montagne Noire, Savoie, Vosges and Rhine Valley. 210Pb soil inventories were used to estimate long-term (>75 yr) deposition of submicron aerosols. Whereas 210Pb total deposition is explained partly by wet deposition, as demonstrated by increase of 210Pb inventory with annual rainfall; a part of 210Pb in the soils of higher altitude is caused by orographic depositions. Using measurements of radionuclides coming from nuclear aerial weapon tests (137Cs and Pu isotopes), we were able to estimate the origin of aerosols deposited in high-altitude sites and to confirm the importance of occult deposition and feeder–seeder mechanism. Using a simple mass balance model, we estimate that occult deposition and feeder–seeder mechanisms account to more than 50% of total deposition of 210Pb and associated submicron aerosols in French altitude sites
Controlled hypercapnia and neonatal cerebral artery Doppler ultrasound waveforms
No full textEleven normal term infants undergoing respiratory assessment involving rebreathing to produce progressive hypercapnia were studied by Doppler ultrasound examination of an anterior cerebral artery during the procedure. A linear increase in end tidal carbon dioxide concentration from 4.5% to a maximum of 8.5% was documented during a period of 4-5 min rebreathing. A corresponding elevation of transcutaneous carbon dioxide tension was shown in the two infants monitored in this way. In all cases the Pourcelot index fell with rising end tidal carbon dioxide concentration. This fall in Pourcelot index was due to an increase in the diastolic frequency of the Doppler waveform. These results are consistent with the view that Pourcelot index correlates with cerebral vascular resistance distal to the site of recording
Characterization and migration of atmospheric REE in soils and surface waters
No full textRainwater and snow collected from three different sites in France (Vosges Mountains, French Alps and Strasbourg) show more or less similar shapes of their REE distribution patterns. Rainwater from Strasbourg is the most REE enriched sample, whereas precipitations from the two mountainous, less polluted catchments are less REE enriched and have concentrations close to seawater. They are all strongly LREE depleted. Different water samples from an Alpine watershed comprising snow, interstitial, puddle and streamwater show similar REE distributions with LREE enrichment (rainwater normalized) but MREE and HREE depletion. In this environment, where water transfer from the soil to the river is very quick due to the low thickness of the soils, it appears that REE in streamwater mainly originate from atmospheric inputs. Different is the behaviour of the REE in the spring- and streamwaters from the Vosges Mountains. These waters of long residence time in the deep soil horizons react with soil and bedrock REE carrying minerals and show especially significant negative Eu anomalies compared to atmospheric inputs. Their Sr and Nd isotopic data suggest that most of the Sr and Nd originate from apatite leaching or dissolution. Soil solutions and soil leachates from the upper soil horizons due to alteration processes strongly depleted in REE carrying minerals, have REE distribution patterns close to those of lichens and throughfall. Throughfall is slightly more enriched especially in light REE than filtered rainwater probably due to leaching of atmospheric particles deposited on the foliage and also to leaf excretion. Data suggest that Sr and Nd isotopes of the soil solutions in the upper soil horizons originate from two different sources: 1) An atmospheric source with fertilizer, dust and seawater components and 2) A source mainly determined by mineral dissolution in the soil. These two different sources are also recognizable in the Sr and Nd isotopic composition of the tree’s throughfall solution. The atmospheric contributions of Sr and Nd to throughfall and soil solution are of 20 to 70 and 20%, respectively. In springwater, however, the atmospheric Sr and REE contribution is not detectable
Izuchenie vliyaniya sulodeksida na endoteliy-zavisimuyu vazodilatatsiyu mozgovykh sosudov u zhivotnykhso streptozototsin-indutsirovannym sakharnym diabetom
No full textAim. To analyse effects of sulodexide on endothelium-dependent vasodilation (EDVD) of brain vessels in animals with experimental diabetes mellitus. Materials and methods. The study was performed on 45 Wistar male rats (180-219 g b.w.) allocated to 3 equal groups. Group 1 served as control, group 2 included rats with DM given physiological saline, group 3 was comprised of animals with DM given sulodexide (30 LRU for 4 weeks). The endothelial dysfunction (ED) was simulated by inducing DM (single v/v injection of 50 mg/kg streptozotocin). A month later, the endothelium-dependent and independent vasodilation was tested by registration of circulation in brain vessels in the projection of the middle cerebral artery, determination of Pourcelot?s and Gosling?s indices before and after administration of 0.001 mg/kg acetylcholine (Acros organics, USA), 300 mg/kg L-arginine (Acros organics, USA), 0.007 mg/kg nitroglycerin (MTKh, Moscow), 10 mg/kg nitro-L-arginine (Acros organics, USA). Samples for immunohistochemical analysis were prepared using antibodies against e-NOS and endothelin-1 (Novocastra TM) as recommended by the manufacturer. STATISTICA/w7.0 program for Windows (StatSoft Inc., USA) was used for basic statistical analysis of the results of all experiments. Results. Administration of acetylcholine to DM rats caused a much greater (2.58-fold) decrease of EDVD than in control animals whereas endothelium-independent vasodilation remained unaltered (following nitroglycerin administration); Pourcelot?s and Gosling?s indices significantly increased. DM rats given sulodexide showed lower Pourcelot?s and Gosling?s indices than untreated animals. Thus, impaired expression of antibodies against e-NOS and enhanced expression of anti-endothelin-1 antibodies (specific markers of endothelial disturbance) suggest development of ED in DM and endothelium protection by sulodexide that increases the eNOS level and decreases the endothelin-1 level thereby improving EDVD. Conclusion. Administration of sulodexide to DM rats increases the eNOS level and decreases the endothelin-1 level thereby improving EDVD
Load in the Achilles tendon is progressively increased with reductions in walking speed
No full textIntroduction: \ud
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Achilles tendon rehabilitation protocols commonly recommend a gradual increase in walking speed to progressively intensify tendon loading. This study used transmission-mode ultrasound to evaluate the influence of walking speed on loading of the human Achilles tendon in vivo.\ud
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Methods: \ud
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Axial transmission speed of ultrasound was measured in the right Achilles tendon of 33 adults (mean ± SD; age, 29 ± 3 years; height, 1.725 ± 0.069 m; weight, 71.4 ± 19.9 kg) during unshod, steady-state treadmill walking at three speeds (slow, 0.85 ± 0.12ms; preferred, 1.10 ± 0.13m/s; fast, 1.35 ± 0.20 m/s). Ankle kinematics, spatiotemporal gait parameters and vertical ground reaction force were simultaneously recorded. Statistical comparisons were made using repeated measure ANOVA models.\ud
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Results:\ud
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Increasing walking speed was associated with higher cadence, longer step length, shorter stance duration, greater ankle plantarflexion, higher vertical ground reaction force peaks and a greater loading rate (P <.05). Maximum (F1,38 = 7.38, P<.05) and minimum (F1,46 = 8.95, P <.05) ultrasound transmission velocities in the Achilles tendon were significantly lower (16-23 m/s) during the stance but not swing phase of gait, with each increase in walking speed.\ud
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Conclusions:\ud
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Despite higher vertical ground reaction forces and greater ankle plantarflexion, increasing walking speed resulted in a reduction in the axial transmission velocity of ultrasound in the Achilles tendon; indicating a speed-dependent reduction in tensile load within the triceps surae muscle-tendon unit during walking. These findings question the rationale for current progressive loading protocols involving the Achilles tendon, in which reduced walking speeds are advocated early in the course of treatment to lower Achilles tendon loads
Rôle du fer et des espèces réactives de l'oxygène dans la prolifération et la différenciation des leucémies aigües myéloblastiques (caractérisation du système régulateur IRE-IRP dans l'homéostasie du fer de deux lignées leucémiques humaines)
No full textLe pronostic des leucémies aiguës myéloblastiques reste très péjoratif malgré les progrès de l intensification thérapeutique. La recherche de nouvelles thérapies ne peut s'affranchir d'une meilleure compréhension des mécanismes de leucémogénèse. Or, l homéostasie du fer et l équilibre d'oxydoréduction sont intimement associés au processus leucémique. Cependant, la relation exacte entre stress oxydant et potentiel tumoral reste encore méconnue. Dans ce contexte, afin d évaluer l'impact des réseaux de régulation du fer et de l équilibre redox sur la prolifération et la différenciation des cellules leucémiques, nous avons déterminé l'état des médiateurs et des réseaux de régulation d'intérêt dans deux modèles de lignées leucémiques humaines (KG1 et K562) avant et après une perturbation telle que la carence en fer. Nos observations des deux modèles leucémiques révèlent que le système IRE-IRP, système régulateur du fer intra-cellulaire, est actif, fonctionnel, et est sous la dépendance de la concentration en fer. Pour la première fois, les cibles de ce système ont été évaluées quantitativement, définissant un profil similaire entre les deux modèles de lignées leucémiques mais également très similaire au profil de cellules CD34+ issues d'un donneur sain. Enfin, à partir des données expérimentales, le seuil de fer nécessaire à la cellule leucémique pour proliférer, a été évalué et estimé. Ce seuil pourrait se révéler d'une importance considérable, dans l'ajustement de la posologie d'agents anti-leucémiques, dans le traitement des patients leucémiques sous chimiothérapie et anémiés, et dans les nombreux cas où un apport de fer au patient est nécessaire.GRENOBLE1-BU Médecine pharm. (385162101) / SudocSudocFranceF
L'action de membranes pour les ∞-opérades cohérentes
No full textWe study the brane action, which endows the space of extensions of the identityof a coherent ∞-operad O with a canonical O-algebra structure in the ∞-category of cospans of spaces.First, we prove that Mann–Robalo’s construction of the brane action ex-tends to general coherent ∞-operads, with possibly multiple colors and non-contractible spaces of unary operations. Second, we establish that Lurie’smodel of the space of extensions of an operation is equivalent to Mann–Robalo’smodel, via an explicit zigzag of homotopy equivalences.In the monochromatic case, contrary to what is claimed in existing liter-ature, we show that the space of extensions in the sense of Lurie is not ingeneral equivalent to the homotopy fiber of the associated forgetful morphism,but rather to its homotopy quotient by the ∞-group of unary operations. Asa consequence of these results, we prove that the ∞-operads of B-framed littledisks are coherent and admit brane actions related to string topology opera-tions.Cette thèse porte sur l’action de membranes, un mécanisme qui munit l’espacedes extensions de l’opération identité dans une ∞-opérade cohérente O d’unestructure canonique de O-algèbre dans l’∞-catégorie des cocorrespondancesd’espaces.Dans un premier temps, on démontre que la construction donnée par Mann–Robalo de cette action s’étend aux ∞-opérades cohérentes générales, sans re-striction sur l’espace des couleurs ni sur celui des opérations unaires. Onétablit ensuite l’équivalence entre les modèles de Lurie et de Mann–Robalo del’espace des extensions d’une opération, en les reliant par un zigzag explicited’équivalences d’homotopie.Dans le cas monochromatique, on démontre que, contrairement à ce quela littérature existante suppose, l’espace des extensions au sens de Lurie n’esten général pas équivalent à la fibre homotopique du morphisme d’oubli associémais en est un quotient homotopique par l’action de l’∞-groupe des opérationsunaires. Comme conséquence de ces résultats, on montre que les ∞-opéradesde petits disques à repères tordues sont cohérentes et admettent une action demembranes reliée aux opérations de topologie des cordes
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