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排序方式: 共有371条查询结果,搜索用时 10 毫秒
71.
Philippe Fragu Colette Brianon Catherine Fourr Jrme Clerc Odile Casiraghi Josette Jeusset Frdrique Omri Sylvain Halpern 《Biology of the cell / under the auspices of the European Cell Biology Organization》1992,74(1):5-18
We attempted to indicate the requirements for biomedical applications of SIMS microscopy. Sample preparation methodology should preserve both the structural and the chemical integrity of the tissue. Furthermore, it is often necessary to correlate ionic and light microscope images. This implies a common methodological approach to sample preparation for both microscopes. The use of low or high mass resolution depends on the elements studied and their concentrations. To improve the acquisition and processing of images, digital imaging systems have to be designed and require both ionic and optical image superimposition. However, the images do not accurately reflect element concentration; a relative quantitative approach is possible by measuring secondary ion beam intensity. Using an internal reference element (carbon) and standard curves the results are expressed in micrograms/mg of tissue. Despite their limited lateral resolution (0.5 microns) the actual SIMS microscopes are very suitable for the resolution of biomedical problems posed by action modes and drug localization in human pathology. SIMS microscopy should provide a new tool for metabolic radiotherapy by facilitating dose evaluation. The advent of high lateral resolution SIMS imaging (less than 0.1 microns) should open up new fields in biomedical investigation. 相似文献
72.
Antisera were raised against tryptophan, 5-hydroxytryptophan, 5-hydroxytryptamine, 5-methoxytryptophan, and 5-methoxytryptamine, by conjugating each molecule to bovine serum albumin and to human serum albumin via glutaraldehyde, in such a way as to preserve the original part. Antibody specificity was tested with the enzyme-linked immunosorbent assay method. The specificity of each anti-indolealkylamine-glutaraldehyde antibody was established with competition experiments by using an adsorbed immunogenic conjugate and indolealkylamines either free or conjugated with poly-L-lysine. The nonconjugated compounds were poorly recognized. In the same way, the nonreduced conjugates always appeared less immunoreactive than the reduced ones. Calculated from the specificity study of each antiserum, the cross-reactivity ratios were found to be smallest for the most immunoreactive conjugates. Thus, a specific immune response was defined for each compound belonging to the same metabolic pathway. 相似文献
73.
Mickaël Causse Jean-Michel Sénard Jean François Démonet Josette Pastor 《Applied psychophysiology and biofeedback》2010,35(2):115-123
The paper deals with the links between physiological measurements and cognitive and emotional functioning. As long as the
operator is a key agent in charge of complex systems, the definition of metrics able to predict his performance is a great
challenge. The measurement of the physiological state is a very promising way but a very acute comprehension is required;
in particular few studies compare autonomous nervous system reactivity according to specific cognitive processes during task
performance and task related psychological stress is often ignored. We compared physiological parameters recorded on 24 healthy
subjects facing two neuropsychological tasks: a dynamic task that require problem solving in a world that continually evolves
over time and a logical task representative of cognitive processes performed by operators facing everyday problem solving.
Results showed that the mean pupil diameter change was higher during the dynamic task; conversely, the heart rate was more
elevated during the logical task. Finally, the systolic blood pressure seemed to be strongly sensitive to psychological stress.
A better taking into account of the precise influence of a given cognitive activity and both workload and related task-induced
psychological stress during task performance is a promising way to better monitor operators in complex working situations
to detect mental overload or pejorative stress factor of error. 相似文献
74.
Estela Romero Josette Garnier Luis Lassaletta Gilles Billen Romain Le Gendre Philippe Riou Philippe Cugier 《Biogeochemistry》2013,113(1-3):481-505
We provide data on nutrient export for 28 rivers in southwestern Europe and analyze long-term changes in the context of anthropogenic pressures and regulation policies. Special attention is given to seasonal variations, because the integrated annual values that are usually provided do not allow us to establish comparisons with seasonal phytoplankton dynamics. The eutrophication risk associated with river inputs is addressed by means of an indicator (Index of Coastal Eutrophication Potential, ICEP, Billen and Garnier, Mar Chem 106:148–160, 2007). An overview of the temporal evolution and the intra-annual variability of the ICEP is discussed for specific rivers and integrated coastal regions. The annual dynamics of the eutrophication indicator is analyzed to delimit those periods when the risk of eutrophication is particularly high. The trends in nutrient fluxes and coastal phytoplankton are compared by means of a case study (Seine Bay). The decrease in phosphorus matches a general decrease in phytoplankton biomass in the summer. However, sustained high values of nitrogen still foster the emergence of harmful algal blooms, and we found an increase in the summer abundance of dinoflagellates. The abatement of phosphorus alone is not enough to shortcut harmful blooms and toxic outbreaks in the Seine Bay. A reduction in nitrogen inputs may be necessary to effectively minimize eutrophication problems. 相似文献
75.
Nicolas Bréchot Elisa Gomez Marine Bignon Jamila Khallou-Laschet Michael Dussiot Aurélie Cazes Cécile Alanio-Bréchot Mélanie Durand Josette Philippe Jean-Sébastien Silvestre Nico Van Rooijen Pierre Corvol Antonino Nicoletti Bénédicte Chazaud Stéphane Germain 《PloS one》2008,3(12)
Background
Macrophages, key regulators of healing/regeneration processes, strongly infiltrate ischemic tissues from patients suffering from critical limb ischemia (CLI). However pro-inflammatory markers correlate with disease progression and risk of amputation, suggesting that modulating macrophage activation state might be beneficial. We previously reported that thrombospondin-1 (TSP-1) is highly expressed in ischemic tissues during CLI in humans. TSP-1 is a matricellular protein that displays well-known angiostatic properties in cancer, and regulates inflammation in vivo and macrophages properties in vitro. We therefore sought to investigate its function in a mouse model of CLI.Methods and Findings
Using a genetic model of tsp-1 −/− mice subjected to femoral artery excision, we report that tsp-1 −/− mice were clinically and histologically protected from necrosis compared to controls. Tissue protection was associated with increased postischemic angiogenesis and muscle regeneration. We next showed that macrophages present in ischemic tissues exhibited distinct phenotypes in tsp-1 −/− and wt mice. A strong reduction of necrotic myofibers phagocytosis was observed in tsp-1 −/− mice. We next demonstrated that phagocytosis of muscle cell debris is a potent pro-inflammatory signal for macrophages in vitro. Consistently with these findings, macrophages that infiltrated ischemic tissues exhibited a reduced postischemic pro-inflammatory activation state in tsp-1 −/− mice, characterized by a reduced Ly-6C expression and a less pro-inflammatory cytokine expression profile. Finally, we showed that monocyte depletion reversed clinical and histological protection from necrosis observed in tsp-1 −/− mice, thereby demonstrating that macrophages mediated tissue protection in these mice.Conclusion
This study defines targeting postischemic macrophage activation state as a new potential therapeutic approach to protect tissues from necrosis and promote tissue repair during CLI. Furthermore, our data suggest that phagocytosis plays a crucial role in promoting a deleterious intra-tissular pro-inflammatory macrophage activation state during critical injuries. Finally, our results describe TSP-1 as a new relevant physiological target during critical leg ischemia. 相似文献76.
77.
M Vincent N Rouvière J Gallay 《Cellular and molecular biology, including cyto-enzymology》2000,46(6):1113-1131
The time-resolved fluorescence intensity and anisotropy decays of the immunophilin domain of FKBP59 (FKBP59-I)--a protein containing two tryptophan residues (the W89, buried in a hydrophobic pocket and the W59, water exposed)--were studied using the time-correlated single photon counting (TCSPC) technique. The synchrotron radiation machine Super-ACO (Orsay, France) was used as a pulsed light source (approximately 8MHz). A mainly dual and discrete excited state lifetime distribution was previously evidenced (Rouvière et al., 1997). The lifetime heterogeneity has been suggested to be relevant to the topological tryptophan heterogeneity. Indeed, taking into account the spectroscopic properties of the single tryptophan residue of the immunophilin FKBP12, a highly homologous protein containing a single tryptophan residue, the short- and the long-lived lifetime species were assumed to be related to the solvent-buried and to the solvent-exposed fluorescent residues, respectively. We definitely demonstrate this point by describing the dynamical properties of each tryptophan residue of the FKBP59-I as a function of the emission wavelength. The data of the polarized components of the fluorescence emission were analyzed by the Maximum Entropy Method using a one-dimensional model (each excited-state lifetime tau being associated with each rotational correlation time theta) and a two-dimensional model (without any a priori association constraint between the tau's and the theta's). The two dimensional analysis of the polarized fluorescence intensity decays by MEM show the existence of a correlation between fast picosecond dynamics of the indole ring with the shortest-lived and blue emitting species. Conversely, the long-lived and red emitting population is mainly associated to the Brownian motion of the protein. A protein flexibility of the region located around the W59 residue, but slightly contributing to the light depolarization process, is also evidenced and can be specifically attributed to the red emitting population. 相似文献
78.
Claude Martin Gerhard Kunesch Josette Martin-Tanguy Jonathan Negrel Michel Paynot Monique Carré 《Plant cell reports》1985,4(3):158-160
Hydroxycinnamoyl putrescines promote the cell multiplication of leaf discs of a tobacco mutant, RMB7, cultivatedin vitro on the Murashige and Skoog medium. This mutant never accumulates these molecules during its development and does not enter in floweirng. Maximal effect is obtained at 2.5·10–4M. The same molecules inhibit bud formation ofNicotiana tabacum var. Xanthi nc, at 5·10–5 M but promote callus formation. From 10–4 M to 5·10–3 M they strongly inhibit cell multiplication and bud formation without toxic effect. Their possible role in plant metabolism is discussed.Abbreviations IAA
indole 3-acetic-acid
- BA
benzyladenine 相似文献
79.
The effects of rolA on root and shoot architecture have been ascribed to a deficiency in gibberellic acid (GA3) and to changes in polyamine metabolism. Using tobacco, we examined interactions among GA3, a polyamine accumulation inhibitor (α-DL-difluoromethylornithine or DFMO) and the rolA gene controlled by the 35S CaMV promoter. We measured the effects of these three agents on architecture and polyamine accumulation in excised roots and whole plants grown in vitro. Previous work showed that DFMO or genetic transformation with the rolA gene from Agrobacterium rhizogenes, controlled by the 35S promoter (P35S-rolA), caused excised tobacco roots to grow faster with altered root system architecture. We show that gibberellic acid (GA3) reversed the effects of DFMO on the architecture of excised root systems, but neither reversed the effects of DFMO on growth, nor the changes in growth and architecture associated with P35S-rolA. GA3 treatment alone resulted in increased agmatine levels, suggesting that the inhibition of the effects of DFMO on architecture was through a stimulation of the arginine decarboxylase (ADC) pathway, GA3 alone also inhibited the accumulation of putrescine and tyramine conjugates in excised roots. In tobacco plants growing in vitro DFMO and P35S-rolA were associated with reduced shoot height, which was partially restored by GA3 treatment; however, GA3 also stimulated shoot height in the controls. GA3 did not lessen the leaf wrinkling associated with P35S-rolA. P35S-rolA increased root number in young seedlings in vitro, and increased root system length in seedlings grown in soil. As in excised roots, the developmental changes linked to DFMO and P35S-rolA were accompanied by reductions in putrescine titers. GA3 treatment stimulated putrescine accumulation in stems and leaves, and partially reversed the negative effects of DFMO and P35S-rolA on putrescine accumulation in roots, stems and leaves. Again, the restoration of putrescine pools appeared to be through a stimulation of the ADC pathway, since agmatine accumulated in plants exposed to GA3. In general, the effects of DFMO and P35S-rolA on phenotype and polyamine metabolism were coordinated, and in many cases these effects were similarly modulated by GA3, reinforcing the previous conclusion that the phenotypic effects of rolA in roots and shoots occur through interference with polyamine metabolism and that the putrescine conjugates are particularly important in regulating root system growth and architecture. We were unable, however, to discem consistent evidence for a direct role for GA3 in establishing the RolA phenotype. 相似文献
80.