Ultrastructural visualization of the transmembranous and cytomatrix-related part of nicotinic acetylcholine receptor of frog motor endplate by means of an immunochemical avidity of IgG for d-tubocurarine.

In the present study, a fine ultrastructural localization of nicotinic acetylcholine receptor (nAChR) was attempted, using d-tubocurarine (d-TC), a quaternary ammonium compound binding to nAChR. The localization was based on the binding avidity of immunoglobulin G (IgG) for acetylcholine (ACh) and other quaternary ammonium compounds, such as d-TC. d-TC was applied to the frog neuromuscular preparation and caused a blockade of neuromuscular transmission. Then, d-TC was rendered insoluble in situ by silicotungstic acid (STA), a precipitating agent of soluble proteins and quaternary ammonium compounds. After tissue fixation, a normal rabbit serum was applied to the fine precipitate of the insoluble salt of d-TC silicotungstate (quaternary ammonium radical of d-TC) to form the immunochemical complex d-TC- rabbit IgG at ACh binding sites. The IgG of the complex was revealed by means of the conventional immunoperoxidase procedure used for ultrastructural localization. Under the electron microscope, fine diaminobenzidine (DAB) precipitates appeared as regular rod-like structures oriented to cytoplasmic side of the horizontal part (crest) of the postsynaptic membrane (between the junctional folds) which is known to be endowed with nAChR. The rod-like precipitates were not observed in the postsynaptic junctional folds which are devoid of nAChR. The distance separating the rods each other was rather constant (12 - 15 nm), while the length of the rods was variable and exceeded the usual length of nAChR. The present work indicates that the rod-like structures, already observed in association with sarcoplasmic side of the postsynaptic membrane, did correspond to the intramembranous and intracytoplasmic part of nAChR and related proteins. These cytochemical results confirm that d-TC binds to ACh binding sites in the pore of nAChR, and raise the question of DAB staining of cytoskeletal proteins related to the nAChR complex

Ultrastructural visualization of the transmembranous and cytomatrix-related part of nicotinic acetylcholine receptor of frog motor endplate by means of an immunochemical avidity of IgG for d-tubocurarine.

In the present study, a fine ultrastructural localization of nicotinic acetylcholine receptor (nAChR) was attempted, using d-tubocurarine (d-TC), a quaternary ammonium compound binding to nAChR. The localization was based on the binding avidity of immunoglobulin G (IgG) for acetylcholine (ACh) and other quaternary ammonium compounds, such as d-TC. d-TC was applied to the frog neuromuscular preparation and caused a blockade of neuromuscular transmission. Then, d-TC was rendered insoluble in situ by silicotungstic acid (STA), a precipitating agent of soluble proteins and quaternary ammonium compounds. After tissue fixation, a normal rabbit serum was applied to the fine precipitate of the insoluble salt of d-TC silicotungstate (quaternary ammonium radical of d-TC) to form the immunochemical complex d-TC- rabbit IgG at ACh binding sites. The IgG of the complex was revealed by means of the conventional immunoperoxidase procedure used for ultrastructural localization. Under the electron microscope, fine diaminobenzidine (DAB) precipitates appeared as regular rod-like structures oriented to cytoplasmic side of the horizontal part (crest) of the postsynaptic membrane (between the junctional folds) which is known to be endowed with nAChR. The rod-like precipitates were not observed in the postsynaptic junctional folds which are devoid of nAChR. The distance separating the rods each other was rather constant (12 - 15 nm), while the length of the rods was variable and exceeded the usual length of nAChR. The present work indicates that the rod-like structures, already observed in association with sarcoplasmic side of the postsynaptic membrane, did correspond to the intramembranous and intracytoplasmic part of nAChR and related proteins. These cytochemical results confirm that d-TC binds to ACh binding sites in the pore of nAChR, and raise the question of DAB staining of cytoskeletal proteins related to the nAChR complex

High IgE sensitization to maize and rice pollen in the highlands of Madagascar

Introduction: maize and rice are two crops constituting the main food supply in many under-developed and developing countries. Despite the large area devoted to the culture, the sensitization to the pollen from these plants is reported to be low and often considered as an occupational allergy. Methods: sixty five Malagasy pollen allergic patients were clinically and immunochemically investigated with regard to maize and rice pollen allergens. Pollen extracts were electrophoretically separated in 1 and 2 dimensions and IgE and IgG reactivities detected upon immunoblotting. Results: when exploring the sensitization profile of Malagasy allergic patients to maize and rice pollen, it appears that a high proportion of these patients consulting during grass pollinating season were sensitized to both pollen as revealed by skin prick testing (62 vs. 59%) and IgE immunoblotting (85 vs. 40%). Several clinically relevant allergens were recognized by patients' serum IgE in maize and rice pollen extracts. Conclusion: the high levels of maize and rice pollen sensitization should be related, in this tropical region, to a specific environmental exposure including i) a proximity of the population to the allergenic sources and ii) a putative exacerbating effect of a highly polluted urban atmosphere on pollen allergenicity. Cross reactivities between wild and cultivated grasses and also between rice and maize pollen are involved as well as some specific maize sensitizations. The presence of dense urban and peri-urban agriculture, in various African regions and worldwide, could be a high environmental risk factor for people sensitive to maize pollen

Evaluation of carrier ampholyte-based capillary electrophoresis for separation of

Carrier ampholyte-based capillary electrophoresis (CABCE) has recently been introduced as an alternative to CE (CZE) in the classical buffers. In this study, isoelectric BGEs were obtained by fractionation of Servalyt pH 4-9 carrier ampholytes to cuts of typical width of 0.2 pH unit. CABCE feasibility was examined on a series of insect oostatic peptides, i.e. proline-rich di- to decapeptides, and phosphinic pseudopeptides - tetrapeptide mimetics synthesized as a mixture of four diastereomers having the -P(O)(OH)-CH2- moiety embedded into the peptide backbone. With identical selectivity, the separation efficiency of CABCE proved to be as good as classical CE for the insect oostatic peptides and better for diastereomers of the phosphinic pseudopeptides. In addition, despite the numerous species present in the narrow pH cuts of carrier ampholytes, CABCE seems to be free of system zones that could hamper the analysis. Peak symmetry was good for moderately to low mobile peptides, whereas some peak distortion due to electromigration dispersion, was observed for short peptides of rather high mobility

Capillary electrophoresis immunoassay using magnetic beads

Protein A-coated magnetic beads (0.3 μm) have been trapped in a small portion of a neutrally coated capillary (50 μm id). Anti-β-lactoglobulin (β-LG) antibodies have then been immobilized on the beads through strong affinity with protein A to subsequently capture β-LG from model or real samples. Once the immunocomplexes formed at physiological pH, a discontinuous buffer system has been used to release the partners and preconcentrate them by transient ITP. The antigens and antibodies have finally been separated by CZE and detected by UV absorbance. An LOQ of 55 nM has been achieved. This methodology has been applied to quantify native β-LG in pasteurized and ultra-high-temperature-treated bovine milk. All the described procedures, including immunosorbent preparation, sample extraction, cleanup, preconcentration, and separation are completely automated on a commercial CE instrument. As this CE immunoassay method is simple, rapid, selective, and sensitive, it should be a practical and attractive technology for the analysis of complicated biological samples

Immunological Interactive Effects between Pollen Grains and Their Cytoplasmic Granules on Brown Norway Rats

International audienceBackgroundGrass pollen is one of the most important aeroallergen vectors in Europe. Under some meteorological factors, pollen grains can release pollen cytoplasmic granules (PCGs). PCGs induce allergic responses. Several studies have shown that during a period of thunderstorms the number of patients with asthma increases because of higher airborne concentrations of PCGs.ObjectiveThe aims of the study were to assess the allergenicity of interactive effects between pollen and PCGs and to compare it with allergenicity of Timothy grass pollen and PCGs in Brown Norway rats.MethodsRats were sensitized (day 0) and challenged (day 21) with pollen grains and/or PCGs. Four groups were studied: pollen-pollen (PP), PCGs-PCGs (GG), pollen-PCGs (PG), and PCGs-pollen (GP). Blood samples, bronchoalveolar lavage fluid, and bronchial lymph node were collected at day 25. IgE and IgG1 levels in sera were assessed by enzyme-linked immunosorbent assay. Alveolar cells, protein, and cytokine concentrations were quantified in bronchoalveolar lavage fluid. T-cell proliferation, in response to pollen or granules, was performed by lymph node assay.ResultsInteractive effects between pollen and PCGs increased IgE and IgG1 levels when compared with those of the negative control. These increases were lower than those of the PP group but similar to the levels obtained by the GG group. Whatever was used in the sensitization and/or challenge phase, PCGs increased lymphocyte and Rantes levels compared with those of the pollen group. The interactive effects increased IL-1α and IL-1β compared with those of the PP and GG groups.ConclusionsImmunologic interactive effects have been shown between pollen and PCGs. For humoral and cellular allergic responses, interactive effects between the 2 aeroallergenic sources used in this study seem to be influenced mainly by PCGs

Identification et stratégie d’élimination des allergènes

L’allergie touche au moins trois grands systèmes physiologiques de notre organisme. Le premier est le système immunitaire, qui produit des anticorps de la classe IgE à la suite de l’exposition à un allergène. Ce sont ces anticorps qui vont nous permettre d’identifier et de suivre à la trace ces allergènes. Une ré-exposition de l’organisme aux mêmes allergènes, touchant le système inflammatoire, va entraîner la libération de médiateurs, en particulier l’histamine, et induire les symptômes de l’allergie. Les effets du système nerveux central sur les deux autres systèmes ne seront pas abordés ici