Influence of acute injection of chloroquine on the biliary secretion of lipids and lysosomal enzyme on rats

Phospholipids and cholesterol combine with a protein fraction (IgA and an acid polypeptide) in bile to form the bile lipoprotein complex. We wished to determine whether lysosomes participated only in IgA secretion or if their secretory role also involved the lipid components of the bile complex. This aspect was studied with a single acute injection of chloroquine, a lysosomotropic drug. The results show that a nonnegligible quantity of IgA travels through the lysosomes. In addition, phospholipid and cholesterol levels undergo a significant (P<0.05) decrease 1 hr after injection before increasing to normal levels. In contrast to the total inhibition of protein secretion (β-glucuronidase, acid phosphatase), a transitory decrease of the secretion of bile lipids takes place that suggest secretory mechanisms involving organelles other than lysosomes.     

Bile lipid secretion in isolated perfused rat liver. A model for metabolic studies

Isolated perfused rat liver was used to study the effects of constant taurocholate perfusion, with or without the addition of phosphatidylcholine unilamellar vesicles, upon both the bile salt-dependent and bile salt-independent secretion of bile. Taurocholate introduction increased bile flow and normalized the bile lipid secretion by restoring the bile salt-dependent secretion. At a flow rate of 30 ml/min, the liver was perfused by a single-pass method. The perfusion medium contained 17.5 μM taurocholate with or without 5.83 μM phosphatidylcholine. In light of a recent quantitative dynamic concept on the interphase partition of lipids, it was calculated that more than99% of the taurocholate reaches the liver as monomers and/or dimers. It was also deduced that the lipids were secreted in bile as small discoidal lipoprotein structures rather than unilamellar lipoproteic vesicles. During the course of the experiments (2 hr), the excellent criteria of viability of this model make it highly suitable for the investigation of hepatic metabolism. Furthermore, the addition of phosphatidylcholine unilamellar vesicles to the perfusate consitutes a potential vector for various liposoluble molecular species.     

Spectral-spatial classification of hyperspectral data based on a stochastic minimum spanning forest approach

In this paper, a new method for supervised hyperspectral data classification is proposed. In particular, the notion of stochastic minimum spanning forest (MSF) is introduced. For a given hyperspectral image, a pixelwise classification is first performed. From this classification map, M marker maps are generated by randomly selecting pixels and labeling them as markers for the construction of MSFs. The next step consists in building an MSF from each of the M marker maps. Finally, all the M realizations are aggregated with a maximum vote decision rule in order to build the final classification map. The proposed method is tested on three different data sets of hyperspectral airborne images with different resolutions and contexts. The influences of the number of markers and of the number of realizations M on the results are investigated in experiments. The performance of the proposed method is compared to several classification techniques (both pixelwise and spectral-spatial) using standard quantitative criteria and visual qualitative evaluation.     

Combining Airborne Photographs and Spaceborne SAR Data to Monitor Temperate Glaciers: Potentials and Limits

Monitoring temperate glacier activity has become more and more necessary for economical and security reasons and as an indicator of the local effects of global climate change. Remote sensing data provide useful information on such complex geophysical objects, but they require specific processing techniques to cope with the difficult context of moving and changing features in high-relief areas. This paper presents the first results of a project involving four laboratories developing and combining specific methods to extract information from optical and synthetic aperture radar (SAR) data. Two different information sources are processed, namely: 1) airborne photography and 2) spaceborne C-band SAR interferometry. The difficulties and limitations of their processing in the context of Alpine glaciers are discussed and illustrated on two glaciers located in the Mont-Blanc area. The results obtained by aerial triangulation techniques provide digital terrain models with an accuracy that is better than 30 cm, which is compatible with the computation of volume balance and useful for precise georeferencing and slope measurement updating. The results obtained by SAR differential interferometry using European Remote Sensing Satellite images show that it is possible to measure temperate glacier surface velocity fields from October to April in one-day interferograms with approximately 20-m ground sampling. This allows to derive ice surface strain rate fields required to model the glacier flow. These different measurements are complementary to results obtained during the summer from satellite optical data and ground measurements that are available only in few accessible points     

Time-related changes of cold-stored rat liver in University of Wisconsin solution. Effect of ursodeoxycholate

Livers of Wistar rats were stored between 0 and 36 hrs. in the University of Wisconsin preservation liquid in order to determine time-related biochemical and morphological hepatic changes. Ursodeoxycholate (100 microM) was also added in the medium to test the hepatoprotective properties of the bile salt. Biochemical assays were performed on hepatic microsomes, plasma and biliary canalicular membranes. Protein and lipid composition of the microsomal and baso-lateral plasma membranes remained stable. Protein and cholesterol content of the biliary canalicular membranes decreased, phospholipid/cholesterol ratio increased between 0 and 36 hrs.; it resulted in a leak of 5'-nucleotidase and leucine amino peptidase activity of these biliary canalicular membranes, especially up to 12 hrs. Between 0 and 36 hrs., the lipid and protein content remained stable in the plasma membranes, as well as both tested enzymatic activities. Observations under electron microscopy showed alterations and underlined fragility of the bile canaliculi, particularly after 24 hrs. preservation. Ultrastructure of sinusoidal membranes showed damaged microvilli. Endoplasmic reticulum remained unchanged, in relation to the stability of the microsomal lipidic, proteic content and hydroxymethylglutaryl-coenzyme A reductase activity, except the decreased protein content after preservation for 36 hrs without ursodeoxycholate. Ursodeoxycholate by itself did not protect against the described disturbances.     

Modification of Ca2+, Mg2+-ATPase and F-actin distribution in hepatocytes of cyclosporine A treated rats. Effect of soyabean lecithin and triacylglycerol

Two oligodeoxynucleotide (oligodN) binding proteins of 100-110 kDa on plasma membranes of human cell lines were recently identified by us. These two proteins seemed to play a role in oligodN uptake. In this study, the impact of the chain length and the sequence of the oligodN on the interaction with those two proteins was investigated. Chain length of oligodN was an important determinant, but not the sole determinant for the interaction. Binding affinity of oligodNs was determined predominantly by base composition, where pyrimidine bases but not purine bases were required in the sequence to retain high affinity. The binding kinetics of the homopolymers of deoxycytidine (dC21) and deoxythymidine (dT21) suggests that the proteins may have different binding sites, with one site preferring thymine bases and the other cytosine bases. Moreover, some additional plasma membrane proteins were identified, with an apparent molecular mass ranging from 40 to 58 kDa, which could bind thymine bases but not cytosine bases.     

A spatial–spectral kernel-based approach for the classification of remote-sensing images

Classification of remotely sensed images with very high spatial resolution is investigated. The proposed method deals with the joint use of the spatial and the spectral information provided by the remote-sensing images. A definition of an adaptive neighborhood system is considered. Based on morphological area filtering, the spatial information associated with each pixel is modeled as the set of connected pixels with an identical gray value (flat zone) to which the pixel belongs: The pixel's neighborhood is characterized by the vector median value of the corresponding flat zone. The spectral information is the original pixel's value, be it a scalar or a vector value. Using kernel methods, the spatial and spectral information are jointly used for the classification through a support vector machine formulation. Experiments on hyperspectral and panchromatic images are presented and show a significant increase in classification accuracies for peri-urban area: For instance, with the first data set, the overall accuracy is increased from 80% with a conventional support vectors machines classifier to 86% with the proposed approach. Comparisons with other contextual methods show that the method is competitive.     

Comparison of Pansharpening Algorithms: Outcome of the 2006 GRS-S Data-Fusion Contest

In January 2006, the Data Fusion Committee of the IEEE Geoscience and Remote Sensing Society launched a public contest for pansharpening algorithms, which aimed to identify the ones that perform best. Seven research groups worldwide participated in the contest, testing eight algorithms following different philosophies [component substitution, multiresolution analysis (MRA), detail injection, etc.]. Several complete data sets from two different sensors, namely, QuickBird and simulated Pleiades, were delivered to all participants. The fusion results were collected and evaluated, both visually and objectively. Quantitative results of pansharpening were possible owing to the availability of reference originals obtained either by simulating the data collected from the satellite sensor by means of higher resolution data from an airborne platform, in the case of the Pleiades data, or by first degrading all the available data to a coarser resolution and saving the original as the reference, in the case of the QuickBird data. The evaluation results were presented during the special session on data fusion at the 2006 international geoscience and remote sensing symposium in Denver, and these are discussed in further detail in this paper. Two algorithms outperform all the others, the visual analysis being confirmed by the quantitative evaluation. These two methods share the same philosophy: they basically rely on MRA and employ adaptive models for the injection of high-pass details.