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Ring-like Structure (ring-like + structure)
Selected AbstractsOH hydrogen abstraction reactions from alanine and glycine: A quantum mechanical approachJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 11 2001Annia Galano Abstract Density functional theory (B3LYP and BHandHLYP) and unrestricted second-order Møller,Plesset (MP2) calculations have been performed using 3-21G, 6-31G(d,p), and 6-311 G(2d,2p) basis sets, to study the OH hydrogen abstraction reaction from alanine and glycine. The structures of the different stationary points are discussed. Ring-like structures are found for all the transition states. Reaction profiles are modeled including the formation of prereactive complexes, and very low or negative net energy barriers are obtained depending on the method and on the reacting site. ZPE and thermal corrections to the energy for all the species, and BSSE corrections for B3LYP activation energies are included. A complex mechanism involving the formation of a prereactive complex is proposed, and the rate coefficients for the overall reactions are calculated using classical transition state theory. The predicted values of the rate coefficients are 3.54×108 L,mol,1,s,1 for glycine and 1.38×109 L,mol,1,s,1 for alanine. © 2001 John Wiley & Sons, Inc. J Comput Chem 22: 1138,1153, 2001 [source] Ultrastructure, development and histochemistry of the polysaccharide-containing subcuticular compartments in Origanum dictamnus L. peltate glandular hairsFLAVOUR AND FRAGRANCE JOURNAL, Issue 4 2010Artemios M. Bosabalidis Abstract Peltate glandular hairs of Origanum dictamnus at the stage of secretion create two subcuticular chambers; one large and bladder-like, at the apex of the head (containing essential oil), and one small and ring-like, at the bottom of the head (containing polysaccharides). In the apical chamber, along with the essential oil, a small lateral compartment containing polysaccharides, also exists. This compartment surrounds peripherally the apical chamber creating a second ring-like structure. The apical plasmalemma of the head cells exhibits a high electron density and presumably has a specific substructure to facilitate passing to the subcuticular chamber of the secretory product. The latter probably exists in the form of glucosides, which, after passing across the plasmalemma and entering the apical chamber, become hydrolysed into the aglycone fraction (essential oil) and the sugar fraction (polysaccharides). Copyright © 2010 John Wiley & Sons, Ltd. [source] Isolation of the plastid FtsZ gene from Cyanophora paradoxa (Glaucocystophyceae, Glaucocystophyta)PHYCOLOGICAL RESEARCH, Issue 2 2005Mayuko Sato SUMMARY Plastids of glaucocystophytes are termed cyanelles and retain primitive features, such as a peptidoglycan wall. We isolated a full-length prokaryotic plastid division gene, FtsZ, from the glaucocystophyte alga Cyanophora paradoxa Korshikov (CpFtsZ-cy). CpftsZ-cy has a chloroplast-targeting signal at the N-teminus. Immunofluorescence microscopy showed that CpFtsZ-cy forms a ring-like structure at the division plane of cyanelles. [source] Videofluoroscopic Swallow Studies in Unilateral Cricopharyngeal Dysfunction,THE LARYNGOSCOPE, Issue 6 2003Stacey L. Halum MD Abstract Objectives/Hypothesis Although the cricopharyngeus muscle is a ring-like structure, unilateral cricopharyngeal dysfunction can produce significant dysphagia. This entity has not been well described in the literature. The aims of the study were to identify the characteristic findings on videofluoroscopic swallow studies in patients with dysphagia secondary to unilateral cricopharyngeal dysfunction, to note the associated vagal nerve injury, and to evaluate patient outcomes following ipsilateral cricopharyngeal myotomy. Study Design Retrospective clinical investigation. Methods The clinic charts, electromyographic tests, videostroboscopic examinations, and videofluoroscopic swallow studies were reviewed from a series of patients who presented to our institution from 1993 to 2001 with dysphagia and findings on videofluoroscopic swallow studies suggestive of unilateral cricopharyngeal dysfunction on posterior,anterior view. In patients treated with ipsilateral cricopharyngeal myotomy, postoperative findings on swallow studies and patient outcomes were also reviewed. Results Eighteen patients demonstrated findings characteristic of unilateral cricopharyngeal muscle dysfunction on videofluoroscopic swallow study. The common feature was a unilateral shelf-like barrier at the cricopharyngeus on the posterior,anterior view with pooling of liquid bolus in the ipsilateral pyriform sinus and episodic shunting to the contralateral side. Eight patients did not have evidence of cricopharyngeal dysfunction (ie, cricopharyngeal bar) on lateral films. Of the 18 patients, 14 had histories consistent with vagal injury secondary to trauma (n = 2), neoplastic involvement (n = 7), iatrogenic injury (n = 2), or central nervous system disease (n = 3). Results of videostroboscopic examinations demonstrated vocal fold motion impairment in 14 patients, and electromyographic test results confirmed unilateral vagal injuries in those who underwent electromyographic testing (n = 6). In the remaining 4 of 18 patients, videostroboscopic examinations demonstrated normal vocal fold abduction but impaired lengthening with a posterior glottic gap, and electromyographic test results (n = 4) indicated unilateral superior laryngeal nerve involvement. Of the 15 patients treated with ipsilateral cricopharyngeal myotomy, 1 patient required postoperative esophageal dilations for an esophageal stricture distal to the cricopharyngeus, whereas the remaining 14 patients had functional resolution of their dysphagia. Conclusion In patients presenting with dysphagia and evidence of unilateral vagal injury, careful assessment of posterior,anterior view on videofluoroscopic swallow study should be included to evaluate for unilateral cricopharyngeal dysfunction. [source] Structure of Escherichia coli YfdW, a type III CoA transferaseACTA CRYSTALLOGRAPHICA SECTION D, Issue 3 2004Arhonda Gogos Crystal structures are reported for free and coenzyme A (CoA) bound forms of the YfdW protein from Escherichia coli, a representative type III CoA transferase. The structures reveal a two-domain protomer with interdomain connections forming a ring-like structure with a large central hole. Two protomers associate to form a highly intertwined dimer in which the hole of each ring is filled by the partner molecule. Each protomer binds a single CoA molecule and these CoA-binding sites are distant from one another in the dimer. [source] Structural Consideration of Mammalian D -Aspartyl EndopeptidaseCHEMISTRY & BIODIVERSITY, Issue 6 2010Tadatoshi Kinouchi Abstract D -Aspartyl endopeptidase (DAEP) is a specific protease for D -aspartic acid (D -Asp)-containing protein, which has been implicated in the pathogenesis of age-related and misfolding diseases such as Alzheimer's disease. Therefore, DAEP would serve as a defensive system against the noxious D -Asp-containing protein. However, it is unclear how DAEP exerts its unique enzymatic function, since its higher-order structure remains quite unsolved. In this study, we analyzed the conformation of purified DAEP from the mitochondrial membrane of mouse by atomic force microscopy the advantage of which is its ability to study biological macromolecules and even living organisms in an ambient air environment. DAEP formed a ring-like structure with a diameter of ca. 40,nm. Our data suggest that DAEP topologically belongs to the AAA+ protease family such as proteasome, Lon, and mitochondrial membrane-bound i-/m-AAA protease. [source] Liesegang rings in fine needle aspirate of breast cysts with predominance of apocrine cells: A study of 14 casesDIAGNOSTIC CYTOPATHOLOGY, Issue 10 2008F.I.A.C., Raj K. Gupta M.D. Abstract Fine needle aspirate (FNA) from 14 cases (age range 17,84 years), with Liesegang rings (LR's) in breast cysts seen over a period of 26 years comprised the material of this study from more than 38,000 FNA's of the breast which had been done for a variety of breast lesions. In six of the 14 cases, the aspirate was obtained under ultrasound guidance whereas in the remaining cases it was collected from a palpable lesion. The aspiration was performed using a 22 gauge needle and the syringe and needle contents were washed in a cytology container with 30% ethyl alcohol in physiologic saline. The cytologic preparations from half of the sample were made on a 5 micron Schleicher and Schuell filter and stained by Papanicolaou method whereas from the remainder of the sample a cell block was made and sections cut, stained with hematoxylin-eosin (H&E) and used for immunohistochemical study. Filter preparations and cell blocks revealed cyanophilic, spherical, ring-like structures of various sizes and shape mostly with double walls, and striations with amorphous material in the lumen and under polarized light were nonrefractile. Seen also were several apocrine cells and some macrophages and the LR's were found to be negative on immunostains for EMA and CK, and a panel of other special stains (Table I). Since LR's can be mistaken for ova, larvae, or parasites, it is important to be aware of their potential presence in aspirate samples of breast cysts to avoid a misdiagnosis. The exact mechanism of formation of LR's is not fully understood and certain views as proposed are discussed in this presentation. Diagn. Cytopathol. 2008;36:701,704. © 2008 Wiley-Liss, Inc. [source] Recombinant newcastle disease virus capsids displaying enterovirus 71 VP1 fragment induce a strong immune response in rabbitsJOURNAL OF MEDICAL VIROLOGY, Issue 8 2006Lalita Ambigai Sivasamugham Abstract The complete VP1 protein of EV71 was truncated into six segments and fused to the C-terminal ends of full-length nucleocapsid protein (NPfl) and truncated NP (NPt; lacks 20% amino acid residues from its C-terminal end) of newcastle disease virus (NDV). Western blot analysis using anti-VP1 rabbit serum showed that the N-terminal region of the VP1 protein contains a major antigenic region. The recombinant proteins carrying the truncated VP1 protein, VP11,100, were expressed most efficiently in Escherichia coli as determined by Western blot analysis. Electron microscopic analysis of the purified recombinant protein, NPt-VP1,100 revealed that it predominantly self-assembled into intact ring-like structures whereas NPfl-VP1,100 recombinant proteins showed disrupted ring-like formations. Rabbits immunized with the purified NPt-VP1,100 and NPfl-VP1,100 exhibited a strong immune response against the complete VP1 protein. The antisera of these recombinant proteins also reacted positively with authentic enterovirus 71 and the closely related Coxsackievirus A16 when analyzed by an immunofluorescence assay suggesting their potential as immunological reagents for the detection of anti-enterovirus 71 antibodies in serum samples. J. Med. Virol. 78:1096,1104, 2006. © 2006 Wiley-Liss, Inc. [source] Self-association of EPEC intimin mediated by the ,-barrel-containing anchor domain: a role in clustering of the Tir receptorMOLECULAR MICROBIOLOGY, Issue 1 2004Thierry Touzé Summary Outer membrane intimin directs attachment of enteropathogenic Escherichia coli (EPEC) via its Tir receptor in mammalian target cell membranes. Phosphorylation of Tir triggers local actin polymerization and the formation of ,pedestal-like' pseudopods. We demonstrate that the intimin protein contains three domains, a flexible N-terminus (residues 40,188), a central membrane-integrated ,-barrel (189,549), and a tightly folded Tir-binding domain (550,939). Intimin was shown by electron microscopy to form ring-like structures with a ,7 nm external diameter and an electron dense core, and to form channels of 50picoSiemens conductance in planar lipid bilayers. Gel filtration, multiangle light scattering and cross-linking showed that this central ,-barrel membrane-anchoring domain directs intimin dimerization. Isothermal titration calorimetry revealed a high affinity, single-binding site interaction of 2 : 1 stoichiometry between dimeric intimin and Tir, and modelling suggests that this interaction determines a reticular array-like superstructure underlying receptor clustering. In support of this model, actin rearrangement induced in Tir-primed cultured cells by intimin-containing proteoliposomes was dependent on the concentration of both intimin and Tir, and co-localized with clustered phosphorylated Tir. [source] The SAURON project , VII.MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2006Integral-field absorption, emission-line kinematics of 24 spiral galaxy bulges ABSTRACT We present observations of the stellar and gas kinematics for a representative sample of 24 Sa galaxies obtained with our custom-built integral-field spectrograph SAURON operating on the William Herschel Telescope. The data have been homogeneously reduced and analysed by means of a dedicated pipeline. All resulting data cubes were spatially binned to a minimum mean signal-to-noise ratio of 60 per spatial and spectral resolution element. Our maps typically cover the bulge-dominated region. We find a significant fraction of kinematically decoupled components (12/24), many of them displaying central velocity dispersion minima. They are mostly aligned and co-rotating with the main body of the galaxies, and are usually associated with dust discs and rings detected in unsharp-masked images. Almost all the galaxies in the sample (22/24) contain significant amounts of ionized gas which, in general, is accompanied by the presence of dust. The kinematics of the ionized gas are consistent with circular rotation in a disc co-rotating with respect to the stars. The distribution of mean misalignments between the stellar and gaseous angular momenta in the sample suggests that the gas has an internal origin. The [O iii]/H, ratio is usually very low, indicative of current star formation, and shows various morphologies (ring-like structures, alignments with dust lanes or amorphous shapes). The star formation rates (SFRs) in the sample are comparable with that of normal disc galaxies. Low gas velocity dispersion values appear to be linked to regions of intense star formation activity. We interpret this result as stars being formed from dynamically cold gas in those regions. In the case of NGC 5953, the data suggest that we are witnessing the formation of a kinematically decoupled component from cold gas being acquired during the ongoing interaction with NGC 5954. [source] Structural and optical characterization of pulsed laser-ablated potassium lithium niobate thin filmsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 12 2009V. Jayasree Abstract Thin films of potassium lithium niobate (K3Li2Nb5O15: KLN) have been prepared on glass substrate, as a function of substrate temperature, using a pulsed laser-deposition (PLD) technique for the first time. Grazing-incidence X-ray diffraction (GIXRD) analysis suggests that KLN films can be grown successfully at a substrate temperature as low as 300,K. The anomalous behavior of the decline of crystalline structure with increase in substrate temperature is explained. The atomic force microscopic (AFM) and scanning electron microscopic (SEM) images show an agglomerated growth mode for the films deposited at a substrate temperature of 300,K and a decrease in grain size with increase in substrate temperature. The films deposited at higher substrate temperatures show ring-like structures. The AFM analysis shows that the rms surface roughness of the film decrease with increase in substrate temperature. The UV,Vis transmission spectra suggest that the nature of the transition in the films is directly allowed. A blue shift in optical bandgap is observed for the films compared to bulk material. The changes in the optical bandgap with substrate temperature are also discussed. [source] | |||||||||||||||||||