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Granule Formation (granule + formation)
Selected AbstractsThe zinc-finger protein ZFR is critical for Staufen 2 isoform specific nucleocytoplasmic shuttling in neuronsJOURNAL OF NEUROCHEMISTRY, Issue 1 2006George Elvira Abstract In mammalian neurons, transport and translation of mRNA to individual potentiated synapses is believed to occur via a heterogeneous population of RNA granules. To identify components of Staufen2-containing granules, we used the yeast two-hybrid system. A mouse fetal cDNA library was screened with the N-terminal fragment of Staufen2 as bait. ZFR, a three zinc finger protein, was identified as an interacting protein. Confocal microscopy showed that ZFR, although mainly nuclear, was also found in the somatodendritic compartment of primary hippocampal neurons where it localized as granule-like structures. Co-localization with Staufen2 was observed in several granules. Biochemical analyses (immunoprecipitation, cell fractionation) further confirmed the ZFR/Staufen2 association. ZFR was shown to interact with at least the Staufen262 isoform, but not with Staufen1. ZFR also co-fractionated with ribosomes and Staufen259 and Staufen252 in a sucrose gradient. Interestingly, knockdown expression of ZFR through RNA interference in neurons relocated specifically the Staufen262, but not the Staufen259, isoform to the nucleus. Our results demonstrate that ZFR is a native component of Staufen2-containing granules and likely plays its role during early steps of RNA transport and localization. They also suggest that one of these roles may be linked to Staufen262 -containing RNA granule formation in the nucleus and/or to their nucleo-cytoplasmic shuttling. [source] Design of granule structure: Computational methods and experimental realizationAICHE JOURNAL, Issue 11 2006Mansoor A. Ansari Abstract The spatial distribution of solid components and porosity within a composite granule,its microstructure,is an important attribute as it carries information about the processing history of the granule and determines its end-use application properties, particularly the dissolution rate. In this work, the problem of rational design of granule structure is formulated, and two methods for its solution are proposed,stochastic design, which is based on random permutation of points within the structure using the simulated annealing algorithm, and variational design, which is based on direct simulation of granule formation from its constituent primary particles, followed by direct simulation of granule dissolution. The variational design method is demonstrated in a case study of the effect of primary particle size, radial distribution of components, and composition of a two-component granule (active, excipient) on the dissolution profile. Selected granule structures designed computationally were also physically made by fluid-bed granulation, their structure analyzed by X-ray micro-tomography, and dissolution curves measured. It was confirmed that the designed structures are feasible to manufacture and that they meet the required dissolution profiles. © 2006 American Institute of Chemical Engineers AIChE J, 2006 [source] The change in characteristics of microcrystalline cellulose during wet granulation using a high-shear mixerJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 5 2001Tatsuya Suzuki The objective of this study was to investigate the mechanism of hard granule formation and to demonstrate the applicability of X-ray diffraction methods for studying the polymeric pharmaceutical excipients. Using a high-shear mixer, microcrystalline cellulose (MCC) was granulated with water as the granulating liquid. The hardness of the MCC granules increased with granulation time and the amount of water added. The specific surface area measured by the N2 adsorption method was reduced during the process. Crystallite size of cellulose, calculated by Scherrer's equation adapted for wide angle X-ray diffraction method, decreased with granulation time and with increasing amounts of water added. Debye plots for X-ray small scattering patterns suggested that the average magnitude of the continuous solid region in MCC granules became significantly greater, whereas the specific surface area of the MCC granules, calculated from Debye plots, became smaller in comparison with that of intact MCC. These findings suggested that the long-chain structures in MCC were disrupted, resulting in smaller units with shorter chain lengths due to the strong shear force of the impeller. These smaller units then form a network within the granules. Thus, MCC granules are strengthened with longer granulation time and greater amounts of water, resulting in a more intricate network. The change in MCC chain length and physical structure can be experimentally detected using the small-angle X-ray scattering and wide-angle powder X-ray diffraction methods. [source] Qualitative disorders of platelets and megakaryocytesJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 8 2005A. T. NURDEN Summary., Qualitative disorders of platelet function and production form a large group of rare diseases which cover a multitude of genetic defects that by and large have as a common symptom, excessive mucocutaneous bleeding. Glanzmann thrombasthenia, is enabling us to learn much about the pathophysiology of integrins and of how ,IIb,3 functions. Bernard,Soulier syndrome, an example of macrothrombocytopenia, combines the production of large platelets with a deficit or non-functioning of the major adhesion receptor of platelets, the GPIb-IX-V complex. Amino acid substitutions in GPIb,, may lead to up-regulation and spontaneous binding of von Willebrand factor as in Platelet-type von Willebrand disease. In disorders with defects in the MYH9 gene, macrothrombocytopenias are linked to modifications in kidney, eye or ear, whereas other inherited thrombocytopenias variously link a low platelet count with a propensity to leukemia, skeletal defects, learning impairment, and abnormal red cells. Defects of secretion from platelets include an abnormal , -granule formation as in the gray platelet syndrome (with marrow myelofibrosis), and of organelle biogenesis in the Hermansky,Pudlak and Chediak,Higashi syndromes where platelet dense body defects are linked to abnormalities of other lysosomal-like organelles including melanosomes. Finally, defects involving surface receptors (P2Y12, TP,) for activating stimuli, of proteins essential for signaling pathways (including Wiskott,Aldrich syndrome), and of platelet-derived procoagulant activity (Scott syndrome) show how studies on platelet disorders are helping unravel the pathways of primary hemostasis. [source] Xanthopterin in the Oriental Hornet (Vespa orientalis): Light Absorbance Is Increased with Maturation of Yellow Pigment GranulesPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2009Marian Plotkin The Oriental hornet bears both brown and yellow colors on its cuticle. The brown component is contributed by the pigment melanin, which is dispersed in the brown cuticle and provides protection against insolation, while the yellow-colored part contains within pockets in the cuticle granules possessing a yellow pigment. These yellow granules (YG) are formed about 2 days prior to eclosion of the imago, and their production continues for about 3 days posteclosion. Xanthopterin is the main component of the granule and lends it its yellow color. Xanthopterin produces a characteristic excitation/emission maximum at 386/456 nm. Characterization by use of mass spectrometry showed the compound to have a molecular ion of 179, as expected from xanthopterin. Spectroscopic examination of the absorption of an entire stripe of yellow cuticle in the course of its metamorphosis revealed that the absorption steadily increases throughout the process to a maximal level of absorption about 3 days posteclosion. In the absence of the YG, the cuticle is permeable to the passage of all wavelengths within the visible range and to the UV range (290,750 nm) in all age groups of hornets. The newly ecloded hornets depart the nest to engage in activities requiring exposure to insolation only as the process of granule formation terminates, namely, when the layer of YG in the cuticle suffices to absorb all the harmful UV radiation. [source] | |||||||||||||