PubMed · 14789960
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
B KARPMAN. 1950. Aggression.. https://doi.org/10.1111/j.1939-0025.1950.tb05470.x
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
Perineuronal nets are lattice-like accumulations of extracellular matrix components around the cell body and perisomatic portion of certain neurons. Whereas interneurons associated to this specific neuron-associated sheath have been elaborately classified, less effort has been undertaken to describe the occurrence of perineuronal nets around pyramidal neurons. Our aim was to give a detailed and comparative description of the occurrence of net-associated pyramidal cells throughout the rat neocortex as well as to systematically and comparatively analyze the relation of main projection types of principal neurons to the presence of perineuronal nets. The present study revealed that perineuronal nets stained with WFA were associated rather rarely to pyramidal cells compared to interneurons in layers II/III and V/VI of rat neocortex. However, their frequency was considerably different between various cortical areas with a maximum in visual cortex and with a minimum in secondary motor cortices. Further analysis revealed that neuron-associated matrix sheaths around principal cells were more common in the primary than in the secondary fields of corresponding areas and they were more numerous in infra-than in supragranular layers in most regions. Subfields of cortical areas also differed regarding the occurrence of net-associated principal cells, and the subtlety of cortical representation seemed to correlate with the frequency of perineuronal nets around pyramidal neurons in the primary somatosensory cortex. It appears that net-associated pyramidal cells do not have a projection pattern restricted to distinct target regions. Rather a functional heterogeneity of the pyramidal cell population contributing to specific intra-or subcortical projections is suggested.
Soybean agglutinin (gSBA) is a tetrameric legume lectin, each of whose subunits are glycosylated. Earlier studies have shown that this protein shows exceptionally high stability in terms of free energy of unfolding when compared to other proteins from the same family. This article deals with the unfolding reactions of the nonglycosylated recombinant form of the protein rSBA and its comparison with the glycosylated counterpart gSBA. The nonglycosylated form features a lower stability when compared to the glycosylated form. Further, the unfolding pathways in the two are widely different. Although the glycosylated form undergoes a simple two-state unfolding, the nonglycosylated species unfolds via a compact monomeric intermediate that is not a molten globule. Representative isothermal and thermal denaturation profiles show that glycosylation accounts for a stabilization of approximately 9 kcal/mol of the tetramer, whereas the difference in T(m) between the two forms is 26 degrees C. Computational studies on the glycan-protein interactions at the noncanonical interface of the protein show that quite a number of hydrogen bond and hydrophobic interactions stabilize the glycoprotein tetramer.
The color changes associated with the aggregation of metal nanoparticles has led to the development of colorimetric-based assays for a variety of target species. We have examined both silver- and gold-based nanoparticles in order to establish whether either metal exhibits optimal characteristics for bioassay development. These silver and gold nanoparticles have been stabilized with a self-assembled monolayer of a mannose derivative (2-mercaptoethyl alpha-d-mannopyranoside) with the aim of inducing aggregation by exploiting the well-known interaction between mannose and the lectin Concanavalin A (Con A). Both metal glyconanoparticles were determined to be ca. 16 nm in diameter (using TEM measurements). Aggregation was observed on addition of Con A to both silver and gold nanoparticles resulting in a shift in the surface plasmon absorption band and a consequent color change of the solution, which was monitored using UV-visible spectrophotometry. Mannose-stabilized silver nanoparticles at a concentration of 3 nM provide an assay for Con A with the largest linear range (between 0.08 and 0.26 microM). Additionally, the kinetic rate of aggregation of the silver-nanoparticle-based bioassay was significantly greater than that of the gold-nanoparticle system. However, in terms of sensitivity, the mannose-stabilized gold-nanoparticle-based assay was optimum with a limit of detection of 0.04 microM Con A, as compared with a value of 0.1 microM obtained for the mannose-stabilized silver nanoparticles. Additionally, a lactose derivative (11-mercapto-3,6,9-trioxaundecyl beta-D-lactoside) was used to stabilize gold nanoparticles to induce aggregation upon addition of the galactose specific lectin Ricinus communis agglutinin (RCA(120)). To examine the specificity of the bioassay, lactose-stabilized gold nanoparticles were mixed with a solution of mannose-stabilized silver nanoparticles to give an aggregation assay capable of detecting two different lectins. When either Con A or RCA(120) was added to the mixed glyconanoparticles, selective recognition of the respective natural ligand was shown by aggregation of a single metal nanoparticle. Centrifugation and removal of the aggregated species enabled further bioassay measurements using the second glyconanoparticle system.