Colloidal Gold Particles (colloidal + gold_particle)

Distribution by Scientific Domains

Selected Abstracts

Postnatal maturation of Na+, K+, 2Cl, cotransporter expression and inhibitory synaptogenesis in the rat hippocampus: an immunocytochemical analysis

Serge Marty
Abstract GABA, a major inhibitory neurotransmitter, depolarizes hippocampal pyramidal neurons during the first postnatal week. These depolarizations result from an efflux of Cl, through GABAA -gated anion channels. The outward Cl, gradient that provides the driving force for Cl, efflux might be generated and maintained by the Na+, K+, 2Cl, cotransporter (NKCC) that keeps intracellular Cl, concentration above electrochemical equilibrium. The developmental pattern of expression of the cotransporter in the hippocampus is not known. We studied the postnatal distribution pattern of NKCC in the hippocampus using a monoclonal antibody (T4) against a conserved epitope in the C-terminus of the cotransporter molecule. We also examined the temporal relationships between the developmental pattern of NKCC expression and the formation of perisomatic GABAergic synapses. This study was aimed at determining, with antivesicular inhibitory amino acid transporter (VIAAT) antibodies, whether perisomatic GABAergic synapses are formed preferentially at the time when GABA is depolarizing. During the first postnatal week, NKCC immunolabelling was restricted to cell bodies in the pyramidal cell layer and in the strata oriens and radiatum. In contrast, at postnatal day 21 (P21) and in adult animals little or no labelling occurred in cell bodies; instead, a prominent dendritic labelling appeared in both pyramidal and nonpyramidal neurons. The ultrastructural immunogold study in P21 rat hippocampi corroborated the light-microscopy results. In addition, this study revealed that a portion of the silver-intensified colloidal gold particles were located on neuronal plasmalemma, as expected for a functional cotransporter. The formation of inhibitory synapses on perikarya of the pyramidal cell layer was a late process. The density of VIAAT-immunoreactive puncta in the stratum pyramidale at P21 reached four times the P7 value in CA3, and six times the P7 value in CA1. Electron microscopy revealed that the number of synapses per neuronal perikaryal profile in the stratum pyramidale of the CA3 area at P21 was three times higher than at P7, even if a concomitant 20% increase in the area of these neuronal perikaryal profiles occurred. It is concluded that, in hippocampal pyramidal cells, there is a developmental shift in the NKCC localization from a predominantly somatic to a predominantly dendritic location. The presence of NKCC during the first postnatal week is consistent with the hypothesis that this transporter might be involved in the depolarizing effects of GABA. The depolarizing effects of GABA may not be required for the establishment of the majority of GABAergic synapses in the stratum pyramidale, because their number increases after the first postnatal week, when GABA action becomes hyperpolarizing. [source]

Differential localization of laminin ,2 and integrin ,4 in primary cultures of the rat gingival epithelium

Michie Tanno
Objectives:, The aim of this study was to investigate the differential immunolocalization of laminin ,2 and integrin ,4 in primary cultures of the rat gingival epithelium. Methods:, The gingival epithelium was obtained from Sprague-Dawley rats and was cultured in serum-free keratinocyte growth medium (DK-SFM). Western blotting analysis, immunofluorescence, confocal laser scanning microscopy (CLSM), and immuno-gold labeling for laminin ,2 and integrin ,4 were employed. CLSM images for laminin and integrin were analyzed in horizontal (x,y axis) and in vertical (x,z axis) sections. Results:, Both laminin ,2 and integrin ,4 were detected by Western blot analysis in the gingival epithelium. Immunolocalization of laminin ,2 was distinct in the cytoplasm to form one or two irregular rings in gingival epithelial cells. By contrast, integrin ,4 was localized diffusely in the cytoplasm. F-actin (indicating actin filaments) was clearly discernible at the periphery of the cytoplasm to form a cellular fringe. In x,z axis images obtained by CLSM, laminin ,2 was recognized as large foci in the most inner portion just above the basal plasma membrane. Integrin ,4 existed in the area where F-actin was labeled surrounding the membrane. Immuno-electron microscopy showed that 10nm colloidal gold particles indicating laminin ,2 were mainly localized at the extracellular portion and in the peripheral cytoplasm, whereas integrin ,4 was distributed in the cytoplasm close to the basal plasma membrane but not in extracellular regions. Conclusions:, In primary cultures of the rat gingival epithelium, both laminin ,2 and integrin ,4 may be produced by the epithelium, and irregular rings of laminin ,2 are formed in areas where gingival cells adhere to the extracellular matrix. [source]

Gastrointestinal persorption and tissue distribution of differently sized colloidal gold nanoparticles

Julián F. Hillyer
Abstract The gastrointestinal uptake of micro- and nanoparticles has been the subject of recent efforts to develop effective carriers that enhance the oral uptake of drugs and vaccines. Here, we used correlative instrumental neutron activation analysis and electron microscopy to quantitatively and qualitatively study the gastrointestinal uptake and subsequent tissue/organ distribution of 4, 10, 28, and 58 nm diameter metallic colloidal gold particles following oral administration to mice. In our quantitative studies we found that colloidal gold uptake is dependent on particle size: smaller particles cross the gastrointestinal tract more readily. Electron microscopic studies showed that particle uptake occurred in the small intestine by persorption through single, degrading enterocytes in the process of being extruded from a villus. To our knowledge this is the first report, at the ultrastructural level, of gastrointestinal uptake of particulates by persorption through holes created by extruding enterocytes. © 2001 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 90:1927,1936, 2001 [source]

Acrosome Biosynthesis in Spermatocytes and Spermatids Revealed by HPA Lectin Cytochemistry

Galder Valbuena
Abstract The origin of the acrosome is controversial, because of both its lysosomal nature and at the moment of its appearance, which seems to be species-specific. Considering the amazing organization shown by the acrosome of some urodele amphibians, HPA-colloidal gold cytochemistry was used to analyze the biogenesis of the acrosome in the urodele Pleurodeles waltl at electron microscopy level. The results showed that HPA-labeling is useful to label the acrosome and its precursor vesicles and, consequently, HPA-histochemistry could be used as a marker of acrosomal content. Labeling of the Golgi apparatus and precursor vesicles was seen in primary spermatocytes and round (stage I) spermatids, thus contributing solid evidence for the beginning of acrosome biogenesis before meiosis. In both primary spermatocytes and round spermatids, an enigmatic vesicle, probably related to the biosynthesis of the neck piece or the tail, was also labeled. Labeling in elongating spermatids (stage II,IV), showed a homogeneous distribution of colloidal gold particles in the acrosomal cap, but the perforatorium was not positive to the lectin. However, in mature (stage V,VI) spermatids, a regional distribution of labeling in the acrosome was seen, with the apical knob showing a stronger labeling than the lateral barb, and the lateral barb showing a stronger labeling than the principal piece of the acrosomal cap. This regional distribution of the labeling suggests that the acrosome develops several domains with different glycoconjugate compositions. Anat Rec, 291:1097-1105, 2008. © 2008 Wiley-Liss, Inc. [source]

Visual detection of IS6110 of Mycobacterium tuberculosis in sputum samples using a test based on colloidal gold and latex beads

P. Upadhyay
Abstract The IS6110 sequence was detected visually in sputum samples of tuberculosis patients using a bi-probe system. One of the probes was an oligonucleotide conjugated to colloidal gold particles, complementary to one end of the target strand. The other probe was an oligonucleotide conjugated to latex beads complementary to the other end of the target strand. In a reaction mix, these two probes bind to the target strand, and the latex beads are then separated by filtration. Bound latex beads have gold colloid particles at the other end of the target strand. These gold colloid particles were made visible to the naked eye by silver autometallography on the ,invisible' colloidal gold particles. The lower detection limit was 50 ng of genomic DNA of Mycobacterium tuberculosis. This new test, together with conventional PCR, was performed on DNA extracted from sputum samples of suspected tuberculosis patients. The new test was simple to perform, the results were visible to the naked eye, and the test was highly specific, as even single point mutations in the target strand sequence could be differentiated. The test could be useful in field-level laboratories because it requires no sophisticated equipment. [source]