The gene encoding α‐1‐acid glycoprotein (AGP), one of the major acute‐phase proteins, is positively controlled at the transcriptional level by cytokines (interleukin‐1 IL‐1, IL‐6, and tumor necrosis ...factor α) and glucocorticoids. Here, we show that growth hormone (GH) treatment of isolated rat hepatocytes in vitro reduces AGP messenger RNA (mRNA) expression. AGP gene expression remained inducible by IL‐1, IL‐6, and phenobarbital (PB) in GH‐treated hepatocytes. Interestingly, the repressive effect of GH on AGP gene expression was also observed in vivo: liver AGP mRNA content was strongly increased in hypophysectomized rats, and GH treatment of these animals led to a decrease in mRNA to levels lower than those in untreated control animals. Moreover, the inhibitory effect of GH mainly occurs at the transcriptional level and can be observed as little as 0.5 hours after GH adding in vitro to isolated hepatocytes. These results show negative regulation of AGP gene expression and strongly suggest that GH is a major endogenous regulator of constitutive AGP gene expression. Moreover, transfection assays showed that the region of the AGP promoter located at position −147 to −123 is involved in AGP gene regulation by GH. Furthermore, GH deeply modifies the pattern of nuclear protein binding to this region. GH treatment of hypophysectomized rats led to the release of proteins of 42 to 45 and 80 kd and to the binding of proteins of 48 to 50 and 90 kd.
Immature density and population size of the biting midge Culicoides belkini (Wirth & Arnaud) were estimated for habitats on Moorea Island, French Polynesia, by means of random, 2- and 3-stage ...sampling designs. Samples were taken in March 1993 from 5 strata of a large larval habitat: a sandy-mud surface of approximately 5,000 m super(2) (stratum 1) in which approximately 12,000 land crab burrows (stratum 2) were counted, a small pond surrounded by approximately 300 m super(2) of muddy bank (stratum 3), and a high organic muddy area (Kopara) of approximately 1,200 m super(2) (stratum 4) with approximately 3,500 crab burrows (stratum 5). Larval density was usually higher in the mud of crab burrows, especially those in the Kopara stratum. Larval density was significantly lower in the sediment of the sandy area as compared with pond banks or Kopara surface. The sampling designs and techniques were logistically adequate, statistically relevant, and were recommended for future studies on C. belkini larval density. Larval habitats were characterized by means of multivariate analysis. Comparison of larval densities with selected environmental variables indicated that larvae density was higher in wet sediments with high levels of organic matter ( approximately 8% of dry weight of sediment) and low salinity ( approximately 0.5-1.5% NaCl equivalents). These variables were considered significant if larval control by means of habitat modification has to be achieved. Nevertheless, C. belkini can tolerate a broad spectrum of variation in the other environmental variables measured and breed in a variety of ecological situations. Therefore, it has a high potential for colonizing new habitats.
The sensitivity of a previously described polymerase chain reaction (PCR) assay was improved to detect a single mosquito, infected by as few as 1–2 microfilariae of
Wuchereria bancrofti, among 20–50 ...uninfected mosquitoes. Wild-caught
Aedes polynesiensis were used to compare assessment of infection by dissection of individuals with the PCR assay of pools of mosquitoes. The PCR assay was at least as sensitivite as dissection for detection of mosquitoes infected with
W. bancrofti.
The solvent effect on the appearance of a red-shifted twisted intramolecular charge-transfer (TICT) emission is studied in molecular clusters. Using a supersonic expansion, dimethylaminobenzomethyl ...ester−acetonitrile (DMABME−(CH3CN) n ) clusters are studied by monitoring at the same time mass spectra and dispersed fluorescence spectra as well as by lifetime measurements. For DMABME−(CH3CN) n clusters, a clear red-shifted fluorescence is observed readily when the cluster contains one solvent molecule and the fluorescence decay becomes biexponential. Short-time evolution of the system has been monitored using a femtosecond pump/probe technique and picosecond photoelectron spectroscopy. The femtosecond dynamics is solvent dependent and is interpreted as a fast decay from the locally excited state to the TICT state reaching an equilibrium between these two states. The equilibrium shifts to the TICT states as the cluster size increases. The role of the triplet state in this process and in the biexponential character of the fluorescence is discussed.
« Chacun de nous appareille vers lui-même, et fait escale chez les autres. » (Fernando Pessoa, 1990 : p 145) Comment combiner exigence méthodologique et nécessité d’avoir recours à des postures ...pragmatiques ? Comment « investir » un terrain lorsque les outils méthodologiques semblent dans un premier temps inadaptés pour l’aborder, le travailler, le scruter ? Il y a des terrains où un engagement strict du chercheur vis-à-vis d’une technique d’enquête ou d’une position doctrinale peut conduire ...
This study evaluates the potential of High Resolution Spotlight TerraSAR-X image for forest type discrimination. Emphasis is put on textural analysis accessible with high resolution radar data. ...Textural attributes are extracted from GLCM matrices, wavelet, and Fourier Transform (i.e. FOTO method). Their contribution for classification is assessed by their performance through the SVM algorithm.
PDF
