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Henri Laudelout Pierre-Charles Simonart René van Droogenbroeck 《Archives of microbiology》1968,63(3):256-277
Summary Calorimetric estimates of the utilization efficiency of the free-energy derived from substrate oxidation by cell suspensions of two nitrifying bacteria, Nitrosomonas and Nitrobacter, provided two ranges of values: 11 to 27% and 15 to 51%, respectively. About 15 to 30% of the utilized free-energy is used for driving endergonic reactions other than CO2 fixation, probably the synthesis of polyphosphates.The molar heat of substrate oxidation does not seem to be influenced by the age of cells harvested during growth or by the length of the incubation period during which cells have been kept in a buffer suspension in a starved condition. The loss of respiratory activity measured either by oxygen uptake or heat evolution in the presence of the specific substrate, nitrite or ammonium, decreases according to kinetics which are influenced by the aerobiosis of the suspension. The viability of the starved cells decreases in a way which is similar to that of the respiratory activity. It seemed impossible to obtain cells which had lost their viability but kept the ability to oxidize their substrate.Two inhibitors of the respiratory chain, quinacrine and cyanide, are without effect on the molar heat of substrate oxidation and consequently on the free-energy utilization efficiency. 2.4 dinitrophenol did decrease the rate of heat evolution during substrate oxidation at concentrations at which the rate of oxygen uptake was not depressed, with the consequences that free-energy efficiency was apparently increased. 相似文献
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Interleukin-1 (IL-1) is a multifunctional cytokine known to act as a growth factor for AIDS-KS cells. In addition to its mitogenic effects, we found that IL-1 induced the protection of KS cells from apoptotic death induced by serum deprivation in a dose-dependent manner. AIDS-KS cells as well as cells derived from iatrogenic and sporadic KS exhibited a similar response to IL-1, which stresses the key role of this cytokine in the pathogenesis of KS regardless of its epidemiological form. Using both an immunohistochemical and an immunoblot approach, we found that IL-1 increased the expression of Bcl-2 and decreased that of Bax, while having no effect on the expression of Bclx(L), Fas and CD40. The effects of IL-1 were inhibited by IL-1ra, suggesting that imbalance between these two counter-acting cytokines may contribute to the altered accumulation of KS spindle cells. Our findings may provide a link between KS cell escape from apoptosis and the immune dysregulation known to be associated with KS. 相似文献
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Delgado-Viscogliosi P Simonart T Parent V Marchand G Dobbelaere M Pierlot E Pierzo V Menard-Szczebara F Gaudard-Ferveur E Delabre K Delattre JM 《Applied and environmental microbiology》2005,71(7):4086-4096
A sensitive and specific method has been developed to enumerate viable L. pneumophila and other Legionella spp. in water by epifluorescence microscopy in a short period of time (a few hours). This method allows the quantification of L. pneumophila or other Legionella spp. as well as the discrimination between viable and nonviable Legionella. It simultaneously combines the specific detection of Legionella cells using antibodies and a bacterial viability marker (ChemChrome V6), the enumeration being achieved by epifluorescence microscopy. The performance of this immunological double-staining (IDS) method was investigated in 38 natural filterable water samples from different aquatic sources, and the viable Legionella counts were compared with those obtained by the standard culture method. The recovery rate of the IDS method is similar to, or higher than, that of the conventional culture method. Under our experimental conditions, the limit of detection of the IDS method was <176 Legionella cells per liter. The examination of several samples in duplicates for the presence of L. pneumophila and other Legionella spp. indicated that the IDS method exhibits an excellent intralaboratory reproducibility, better than that of the standard culture method. This immunological approach allows rapid measurements in emergency situations, such as monitoring the efficacy of disinfection shock treatments. Although its field of application is as yet limited to filterable waters, the double-staining method may be an interesting alternative (not equivalent) to the conventional standard culture methods for enumerating viable Legionella when rapid detection is required. 相似文献
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Sans résuméCommunication présentée au Congrès Int. de Dermatologie Tropicale, Naples, 8–13 juin 1964. 相似文献
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Pilar Delgado-Viscogliosi Tristan Simonart Virginie Parent Grégory Marchand Marie Dobbelaere Eric Pierlot Véronique Pierzo Florence Menard-Szczebara Elisabeth Gaudard-Ferveur Karine Delabre Jean Marie Delattre 《Applied microbiology》2005,71(7):4086-4096
A sensitive and specific method has been developed to enumerate viable L. pneumophila and other Legionella spp. in water by epifluorescence microscopy in a short period of time (a few hours). This method allows the quantification of L. pneumophila or other Legionella spp. as well as the discrimination between viable and nonviable Legionella. It simultaneously combines the specific detection of Legionella cells using antibodies and a bacterial viability marker (ChemChrome V6), the enumeration being achieved by epifluorescence microscopy. The performance of this immunological double-staining (IDS) method was investigated in 38 natural filterable water samples from different aquatic sources, and the viable Legionella counts were compared with those obtained by the standard culture method. The recovery rate of the IDS method is similar to, or higher than, that of the conventional culture method. Under our experimental conditions, the limit of detection of the IDS method was <176 Legionella cells per liter. The examination of several samples in duplicates for the presence of L. pneumophila and other Legionella spp. indicated that the IDS method exhibits an excellent intralaboratory reproducibility, better than that of the standard culture method. This immunological approach allows rapid measurements in emergency situations, such as monitoring the efficacy of disinfection shock treatments. Although its field of application is as yet limited to filterable waters, the double-staining method may be an interesting alternative (not equivalent) to the conventional standard culture methods for enumerating viable Legionella when rapid detection is required. 相似文献
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Conclusions Par l'emploi de substrats radioactifs, il a été possible de montrer que le glucose, le ray-grass tel quel, la fraction soluble, les hemicelluloses et la fraction cellulosique du ray-grass ne sont pas, dans les conditions expérimentales appliquées, entièrement transformés en CO2 dans le sol après une période de deux mois.La décomposition du glucose est plus rapide que celle des hemicelluloses et celle-ci est plus rapide que celle de la fraction cellulosique. Pour le glucose et pour la fraction cellulosique, 11% et 15% respectivement ne se retrouvent pas sous forme de C14O2 tandis que pour la fraction soluble, pour les hemicelluloses et pour le ray-grass tel quel, c'est près de 20% qui ne sont pas oxydés en CO2.La décomposition de chacun de ces substrats radioactifs donne encore lieu à la production de produits organiques radioactifs que l'on trouve dans la fraction des substances solubles, dans la fraction groupant l'- et le -humus et dans l'humine. La radioactivité de cette dernière fraction est du même ordre de grandeur que la somme des deux autres fractions.Travail effectué sous les auspices de l'Institut pour l'Encouragement de la Recherche Scientifique dans l'Industrie et l'Agriculture (I.R.S.I.A.). 相似文献
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Isolation of protein from humic acid extracted from soil 总被引:1,自引:0,他引:1
Summary Chromatography of humic acid in a phenol containing solvent system reveals, in the case of the three types of soil analyzed, the presence of humoprotein containing 11 per cent of nitrogen. Isolation of a humoprotein complex from humic acid, according to the method used by Kirby, followed by paper chromatography allowed the isolation of a protein fraction containing 14.8 per cent nitrogen. This fraction is not dialysable; it has a maximum absorption in ultraviolet light between 260–280 mµ, a small electronegative charge and gives rise to twenty different amino acids. This is the first time that a protein has been separated from humus. Thereby demonstrating that part of the nitrogen contained in humic acid is in the form of protein protected from decomposition.Research supported by the Institut pour l'Encouragement de la Recherche Scientifique dans l'Industrie et l'Agriculture (I.R.S.I.A.). 相似文献
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Thierry Simonart Chantale Degraef Patrick Stordeur Jean-Christophe Noel Roger Mosselmans Jean-Paul Van Vooren 《Free radical research》2013,47(3):221-235
Iron is suspected to be involved in the induction and/or progression of various human tumors. The present study was designed to investigate the effects of iron on endothelial cells, keeping in mind that the homeostasis of microvessels plays a critical role in neo-angiogenesis. Applying a model of human dermal microvascular endothelial cell terminal differentiation and death induced by serum deprivation, we found that iron salts (iron chloride and ferric nitrilotriacetate) provided a survival advantage to endothelial cells. Using immunohistochemistry and Western Blot analysis, we found that the extended cellular life span induced by iron was paralleled by an increase of Bcl-2 protein expression. Taken together, these observations suggest that iron may give a survival advantage to endothelial cells and represent a novel mechanism through which iron may contribute to tumorigenesis. 相似文献
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Résumé
Aspergillus oryzae transforme rapidement l’ammoniaque en groupement aminé.
Lorsqu’une colonie préformée de cette moisissure se cultive sur une solution du sel ammoniacal d’un des acides suivants: acides
acétique, pyruvique, succinique, fumarique, α-cétoglutarique ou encore sur glucose en présence de sulfate ammonique, on trouve
dans le mycélium plusieurs acides aminés, à l’état libre. Dans ces conditions, on y décèle toujours l’alanine, l’acide aspartique,
l’acide glutamique et la glutamine; en outre on y met éventuellement en évidence d’autres acides aminés tels glycine, sérine,
arginine, acide γ-aminobutyrique.
L’acétate, le pyruvate, le succinate et le fumarate ammoniques, donnent lieu respectivement à l’apparition de plus nombreux
acides aminés libres dans le mycélium que la glycine, l’alanine et l’acide aspartique.
Les diverses substances essayées paraissent équivalentes en tant que sources de carbone, ce qui fait aussi ressortir le r?le
des réactions de transamination dans le métabolisme étudié.
Part I, II: Antonine van Leeuwenhoek19, 121, 245, 1953. 相似文献