Search

Les médicaments à consonance ou d’apparence semblables (look-alike, sound-alikeou « LASA ») sont des médicaments dont le nom ou l’apparence peuvent prêter à confusion et qui peuvent conduire à des évènements indésirables graves. Plusieurs erreurs de dispensation ou d’administration ont été déclarées dans notre établissement ces dernières années (exemple : hydroxyzine/hydrochlorothiazide).

Il existe peu de données publiées évaluant la contamination interne des travailleurs agricoles intervenant sur des cultures traitées par des pesticides. L’évaluation du risque résiduel en rentrée relève de la responsabilité de l’employeur. Toutefois, ses moyens d’action dans ce domaine sont limités et les autorisations de mise sur le marché des produits phytosanitaires mentionnent généralement le port d’équipements de protection individuelle en rentrée, mais sans délai après application du traitement et sans distinction des travaux.

In budding yeast, the cortical structure formed by the septins is remodeled at the onset of mitotic exit and delineates a specialized compartment dedicated to cytokinesis. How this septin function is spatially and timely regulated remains poorly understood. In this study, we report a role of the anillin-like protein Bud4 in the formation and the disassembly of the double ring structure formed by the septins at the time of cytokinesis. Bud4 acts with Bud3 in this pathway and in parallel with septin phosphorylation by the p21-activated kinase Cla4 and the septin-dependent kinase Gin4. In addition, we show that the function of Bud4 is regulated by the cyclin-dependent protein kinase Cdk1, the master regulator of cell cycle progression. This result suggests that the Cdks, or a locally specific pool of the kinase, may have a role past mitotic exit.

The outer membrane of Gram-negative bacteria acts as a barrier against harmful lipophilic compounds and larger molecules unable to diffuse freely through the porins. However, outer membrane proteins together with the Tol-Pal and TonB systems have been exploited for the entry of macromolecules such as bacteriocins and phage DNA through the Escherichia coli cell envelope. The TonB system is involved in the active transport of iron siderophores and vitamin B12, while no more precise physiological role of the Tol-Pal system has yet been defined than its requirement for cell envelope integrity. These two systems, containing an energized inner membrane protein interacting with outer membrane proteins, share similarities.

The bacterial twin arginine translocation (Tat) pathway is capable of exporting cofactor-containing enzymes into the periplasm. To assess the capacity of the Tat pathway to export heterologous proteins and to gain information about the property of the periplasm, we fused the twin arginine signal peptide of the trimethylamine N-oxide reductase to the jellyfish green fluorescent protein (GFP). Unlike the Sec pathway, the Tat system successfully exported correctly folded GFP into the periplasm ofEscherichia coli.Interestingly, GFP appeared as a halo in most cells and occasionally showed a polar localization in wild type strains. When subjected to a mild osmotic up-shock, GFP relocalized very quickly at the two poles of the cells. The conversion from the halo structure to a periplasmic gathering at particular locations was also observed with spherical cells of theΔrodA-pbpAmutant or of the wild type strain treated with lysozyme. Therefore, the periplasm is not a uniform compartment and the polarization of GFP is unlikely to be caused by simple invagination of the cytoplasmic membrane at the poles. Moreover, the polar gathering of GFP is reversible; the reversion was accelerated by glucose and inhibited by azide and carbonyl cyanidem-chlorophenylhydrazone, indicating an active adaptation of the bacteria to the osmolarity in the medium. These results strongly suggest a relocalization of periplasmic substances in response to environmental changes. The polar area might be the preferential zone where bacteria sense the change in the environment.

The presence in human gastric juice of a lipase secreted by the gastric mucosae has been reported previously, but its exact cellular origin has not yet been established. Polyclonal antibodies specific to human gastric lipase (HGL) were prepared, and used by an immunofluorescence technique to label cells producing HGL. This immunocytolocalization was correlated with that of pepsin (chief cells) and parietal cells using specific polyclonal or monoclonal antibodies.

We present five cases with confirmed diagnosis of pulmonary alveolar microlithiasis that illustrate the appearance of this rate chronic lung dis-ease on conventional and high-resolution CT. Pulmonary alveolar microlithi-asis is characterized by widespread intraalveolar calcification of both lungs. Conventional CT confirmed the inferior and posterior predominance of the lesions in four of our cases and showed an exceptionally high concentration of microliths in the subpleural parenchyma and along the bronchovascular bundles. High-resolution CT revealed a perilobular and bronchovascular distribution of the disease process at the level of the secondary pulmonary lobule. This pattern correlated closely with pathologic findings.

In an attempt to elucidate the origin of the so-called idiopathic spontaneous pneumothorax (ISP), clinical examination, pulmonary function tests, and computed tomography (CT) with visual quantification and density analysis were performed in 20 young patients two months after an ISP episode. Twenty controls were recruited for CT. The chest roentgenograms were normal in the two groups. The results indicated the presence of various types of emphysematous lesions (EL) in the ISP group located predominantly in the apical fields with subpleural location in 16 patients. Interestingly, diffuse but moderate centrilobular emphysema was noted in 12 of 20 patients. The EL visual quantification was always less than 5 percent of the CT slices’ total areas. The lung mean density shifted significantly toward the air density in the patient group (patients: -743 ± 57.5 HU vs controls -713 ± 59.5 HU, p<0.01). These findings suggest that CT may be useful for early assessment of EL in patients with ISP.

The filamentous brush border glycocalyx forming the 'enteric surface coat' of the intestinal epithelium is composed in rabbits of a 400 kDa mucin-type glycoprotein, which was purified using the 3A4 monoclonal antibody. This monoclonal antibody recognizes a filamentous brush border glycocalyx-specific glycosidic structure containing an O-acetylated sialic acid, which is absent from all the other glycoproteins in the epithelium, with the exception of certain goblet cell mucins. Here we establish that only 50% of the rabbits tested synthesized this glycosidic structure. Upon immunolabeling surface epithelia and sections of jejunum from these rabbits, the carbohydrate epitope recognized by the 3A4 mAb was found to be present on the filamentous brush border glycocalyx of a variable number of enterocytes, which were patchily distributed over all the villi. This heterogeneous expression of 3A4 antigenicity, which was also observed in the crypts, suggests the existence of differences between the patterns of differentiation of enterocytes, which results in the expression of different pools of glycosyltransferases and/or acetyl transferases. In mature enterocytes, the 3A4 determinants were present only on the filamentous brush border glycocalyx, which is anchored solely to the membrane microdomain at the tip of brush border microvilli. However, expression of 3A4 antigenicity begins in the median third of crypts, in enterocytes with a short, thin brush border devoid of apical filamentous brush border glycocalyx. Here the 3A4 epitopes were present over the whole brush border membrane.(ABSTRACT TRUNCATED AT 250 WORDS)

Four different mutations were obtained by selecting for resistance to colicin N and screening for continued production of the OmpF protein of Escherichia coli. Two of them also conferred resistance to colicin A. The substitutions C for R-168 (R168C) and E284K caused the loss of the E21 epitope, while the transition G285D altered the E18, E19, and E20 antigenic sites. The substitution G119D drastically affected the stability of the trimeric conformation.

Dog gastric lipase (DGL) secretion is stimulated in vivo by urecholine, pentagastrin, histamine, 16,16-dimethyl prostaglandin E2, and secretin. Under fasting conditions, DGL is irreversibly inactivated by gastric acid below pH 1.5; consequently, DGL output can be underestimated. This problem has been resolved by buffering the acid or by using an antisecretory drug such as omeprazole during stimulation. There is a clear parallelism between the secretion of DGL and of gastric mucus. This observation led to the present investigation of the cellular localization of DGL using immunofluorescence techniques. Results showed that DGL is cytolocalized in mucous pit cells of gastric glands. Pepsinogen is found in chief cells. To the authors' knowledge, this is the first description of an enzyme (gastric lipase) secreted by mucous-type gastric cells. In contrast to other species, gastric lipase of the dog is located in cardiac, fundic, and antral mucosae.

The Kouroumari, an endoreic plain situated in Mali, is composed of deposits from the Niger River. In this confined area, river water are concentrated by exposure to the arid climate. This results in precipitation of calcite and in waters that tend toward alkalinity. The conventional method used for calculating the activity of aqueous species in solution indicates an oversaturation of water with respect to gibbsite, which is lacking in these soils and never precipitates in such areas. Using these results, it was not possible to determine the mechanisms governing the variation of dissolved Si, Al, and Mg molalities with time. By taking into account the aluminium complex Al13O4(OH)28, inherited kaolinite and illite are shown to dissolve. The control of dissolved Si, Al, and Mg molalities is shown to be related to the formation of magnesium montmorillonite.

An aminopeptidase N has been detected by immunofluorescence in the apical plasma membrane of porcine thyroid cells, facing the follicular lumen. Freshly isolated cells obtained by tissue trypsinization, lose their polarity and exhibit a homogeneous enzyme distribution over the whole plasma membrane. In thyrotropin-stimulated cultured cells organized into follicles, the enzyme is localized in the apical cell pole. In monolayer cells, on the other hand, the enzyme is distributed over the whole surface facing the medium. In both types of cultures fluorescence is also observed in intracytoplasmic organelles. In vivo, aminopeptidase is a marker of the apical part of the thyroid plasma membrane, but its in vitro localization depends upon cell differentiation related to the culture conditions.

The localization of hydrogenase protein in Desulfovibrio gigas cells grown either in lactate-sulfate or hydrogen-sulfate media, has been investigated by subcellular fractionation with immunoblotting and by electron microscopic immunocytochemistry. Subcellular fractionation experiments suggest that no integral membrane-bound hydrogenase is present in D. gigas. About 40% of the hydrogenase activity could be extracted by treatment of D. gigas cells with Tris-EDTA buffer. The rest of the soluble hydrogenase activity (50%) was found in the soluble fraction which was obtained after disruption of Tris-EDTA extracted cells and high speed centrifugation. Both soluble hydrogenase fractions purified to homogeneity showed identical molecular properties including the N-terminal aminoacid sequences of their large and small subunits. Polyacrylamide gel electrophoresis of the proteins of the subcellular fractions revealed a single band of hydrogenase activity exhibiting the same mobility as purified D. gigas hydrogenase. Western blotting carried out on these subcellular fractions revealed crossreactivity with the antibodies raised against (NiFe) hydrogenase. The lack of crossreactivity with antibodies against (FE) or (NiFeSe) hydrogenases, indicated that only (NiFe) type hydrogenase is present in D. gigas.

A large number of mutants introducing point mutations and deletions into the COOH-terminal domain of colicin A have been constructed by using site-directed mutagenesis. The COOH-terminal domain carries the channel activity. The effects of the alterations in the polypeptide chain on the secretion of colicin A by colicinogenic cells have been investigated. All deletions and some mutations were found to lead to protein aggregation in the cytoplasm, thereby preventing release into the medium. The mutated colicin A proteins have been purified, and their activity in vivo (on sensitive cells) and in vitro (in planar lipid bilayers) has been assayed. Deletions in the region containing putative helices 4, 5, and 6 (predicted to be involved in pore formation) and the transitions (Ala----Asp-492, Phe----Pro-493) in helix 4 abolished the activity. No correlation was observed between mutations leading to protein aggregation and those leading to loss of channel activity. Some mutations were found to alter characteristic properties of the single channels, such as stability, current-relaxation kinetics, voltage dependence, and pore conductance. Site-directed mutagenesis provides a powerful tool for studying structure-function relationships of voltage-sensitive ionic channels.

The subcellular localization of beta‐lactamase produced by a secretion‐cloning vector pIN‐III was studied by immunolabelling of frozen thin sections of Escherichia coli. Using double immuno‐gold detections and internal reference proteins, it is shown here that beta‐lactamase encoded by this vector can be exported and that its overproduction leads to aggregation within the periplasm. This aggregation induces the appearance of electron‐dense areas immunolabelled by the antiserum directed against the beta‐lactamase at the external side of the cytoplasmic membrane. The overproduced enzyme is also secreted to the medium in vesicles budding from the outer membrane of lpp strains.

The effects of temporary calcium deficiency on the growth and mineral nutrition of whole tomato (Lycopersicon esculentum All. cv. Rondello) plants were investigated at the 22-23 leaf stage. Three deficiency period durations (5, 8, and 10 days or -Ca5, -Ca8, and -Ca10, respectively) were tested during the two series of hydroponic experiments in a greenhouse. At the end of the calcium deficiency period, the plants were supplied again with a standard nutrient solution. In the plants subjected to a 5-day calcium deficiency, stem growth and new leaf formation were slowed 10-12 days after the onset of the treatment. The effect was rapidly attenuated and no visual symptom was observed thereafter. The stem growth slow-down induced by treatments -Ca8 and -Ca10 8-10 days after the onset of calcium deficiency was followed by the rapid appearance of visual symptoms and by the death of the apical meristem. Thus, beyond five days, even though the plant was supplied again with calcium, the appearance of visual symptoms shortly preceded the total necrosis of the apical meristem of the stem. Two major phenomena were characterized by the analysis of plant uptake and contents. The calcium deficiency showed the occurrence of a strong calcium-magnesium antagonism mainly localized in the leaves, which suggests the influence of calcium on magnesium translocation to the above-ground parts. Besides, in the absence of calcium in the nutrient solution, phosphorus uptake was decreased as shown by the decreased root content. The phenomenon might be related to the occurrence of precipitated dicalcium phosphate at the root surface. The precipitate was likely to constitute a calcium reserve which was rapidly depleted by the plant after a 5-day deficiency.

Root absorption selectivity, which refers to the fact that the mineral elements are not found in the same proportions in the plant as in the growth medium, was characterized using plots where the proportions between the elements were considered. Grain sorghum was grown hydroponically in nutrient solutions where the cationic macroelements were increasingly replaced with sodium and the anionic macronutrients with chloride. The data obtained from the analyses of the nutrient solutions and of the whole plants show that root selectivity promotes the absorption of K+ and NO3- -N and impedes that of Ca++ whereas there is nearly no selectivity towards the other nutrients (Mg, P, S).The high negative selectivity towards unessential elements (Na and Cl) is reflected by their very low proportions within the plant.The comparison between the various plant organs shows that the proportions of the essential elements are nearly identical in the roots, the sheaths, the younger leaves and in the adult leaves (only for the anions). The differences observed for the older leaves are to be assigned to their senescence status which conditions the possibilities of translocation of the elements within the plant.

The filamentous brush border glycocalyx forming the “enteric surface coat” of the intestinal epithelium is composed in rabbits of a 400 kDa mucin-type glycoprotein, which was purified using the 3A4 monoclonal antibody. This monoclonal antibody recognizes a filamentous brush border glycocalyx-specific glycosidic structure containing an O-acetylated sialic acid, which is absent from all the other glycoproteins in the epithelium, with the exception of certain goblet cell mucins. Here we establish that only 50% of the rabbits tested synthesized this glycosidic structure. Upon immunolabeling surface epithelia and sections of jejunum from these rabbits, the carbohydrate epitope rec ognized by the 3A4 mAb was found to be present on the fil amentous brush border glycocalyx of a variable number of enterocytes, which were patchily distributed over all the villi. This heterogeneous expression of 3A4 antigenicity, which was also observed in the crypts, suggests the existence of differences between the patterns of differen tiation of enterocytes, which results in the expression of different pools of glycosyltransferases and/or acetyl trans ferases. In mature enterocytes, the 3A4 determinants were present only on the filamentous brush border glycocalyx, which is anchored solely to the membrane microdomain at the tip of brush border microvilli. However, expression of 3A4 antigenicity begins in the median third of crypts, in enterocytes with a short, thin brush border devoid of apical filamentous brush border glycocalyx. Here the 3A4 epitopes were present over the whole brush border membrane. A few cells higher up, the hyperpolarized expression of filamentous brush border glycocalyx, i.e. its segregation at the tip of the microvilli, began and both the apical filamentous brush border glycocalyx and the whole brush border membrane were labeled with the 3A4 mAb. The labeling of the lateral membrane of microvilli gradually decreased and then disappeared during the migration of the cells to the upper part of the crypts. The 3A4 structure was also detected in some of the granules of some rare goblet cells in the vicinity of the most deeply located labeled enterocytes, whereas no labeled goblet cells were ever observed at higher cell locations.

The immunity protein to colicin A protects producing cells from the action of this pore-forming toxin. It is located into the cytoplasmic membrane. This protein has been ‘tagged’ with an epitope from the colicin A protein for which a monoclonal antibody is available. The fusion protein (named VL1) has been purified after extraction from the membrane in two steps using a chromatofocusing and an immunoadsorbant chromatography. The purified protein has then been reconstituted into lipid vesicles.