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Solid-state NMR study of the transformation of octacalcium phosphate to hydroxyapatite: A mechanistic model for central dark line formation

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JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 2006年第21期128卷 6909-6918页

作者： Tseng, Yao-Hung Mou, Chung-Yuan Chan, Jerry C. C. Natl Taiwan Univ Dept Chem Taipei Taiwan Natl Taiwan Univ Ctr Condensed Matter Taipei Taiwan

For many years, octacalcium phosphate (OCP) has been postulated as the precursor phase of biological apatite in bones and teeth. In this work, we study the molecular mechanism of OCP to hydroxyapatite (HAp) transformation in vitro by several physical techniques, with particular emphasis on solid-state P-31 homonuclear double-quantum (DQ) NMR spectroscopy. The in vitro system is prepared by mixing urea, sodium phosphate monobasic dehydrate, and calcium nitrate tetrahydrate at 100 C. The images obtained by scanning electron microscopy and transmission electron microscopy show that the bladelike OCP crystals will transform into hexagonal rod-shaped HAp crystals as the pH of the reaction mixture increases slowly from 4.35 to 6.69 in 12 h. Powder X-ray diffraction patterns indicate that a trace amount of monetite was also precipitated when the pH was around 5. Together with computer-assisted lattice matching, our DQ NMR data reveal that OCP crystals transform to HAp topotaxially, where the [0001](HAp) and [2110](HAp) axes are along the same directions as the [001](OCP) and [010](OCP) axes, respectively. On the basis of our in vitro results, the formation of the central dark line commonly found in biological hard tissues could be explained by the inherent lattice mismatch between OCP and HAp. Furthermore, the data of the P-31{H-1} cross-polarization NMR suggest that water molecules enter the hydration layers of OCP crystals via the hydrolysis reaction HPO42-+OH- = PO43- + H2O, which also accounts for the deprotonation of the HPO42- ions during the transformation.

关键词： Calcium Compounds/chemistry Calcium Compounds/metabolism Calcium Phosphates/chemistry Calcium Phosphates/chemistry Calcium Phosphates/metabolism Calcium Phosphates/metabolism Crystallization Durapatite/chemistry Durapatite/chemistry Durapatite/metabolism Durapatite/metabolism image processing, computer-assisted Magnetic Resonance Spectroscopy/methods Mechanics Microscopy, Electron, Transmission Nitrates/chemistry Nitrates/metabolism Phosphates/chemistry Phosphates/chemistry Phosphates/metabolism Phosphates/metabolism Urea/chemistry Urea/metabolism X-Ray Diffraction

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MICROTOMOGRAPHY FROM LIMITED PROJECTIONS IN CONVENTIONAL TEM FOR 3D RECONSTRUCTION OF AN INTACT CELL

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ULTRAMICROSCOPY 1988年第4期25卷 293-301页

作者： NELSON, AC HOBBIB, WM Bioengineering University of Washington Seattle 98195.

It is possible to generate three-dimensional reconstructions of whole, non-sectioned biological cells in conventional TEM using an 80 kV tungsten source. A TEM specimen stage was modified to accommodate a precise single-axis tilting mechanism controlled by a digital stepping motor interfaced to a computer. For image collection, a video camera was optically coupled to the TEM phosphorescent screen, and the video image was digitized by a frame buffer interfaced to a computer. Specimen tilt and projection image collection were fully computer-automated. This microtomography system design could be readily adapted for most TEMs. image reconstruction was achieved through computation on projection images from limited tilts;typically less than thirty projection images were needed for a coarse 3D reconstruction. The iterative reconstruction algorithm used certain statistical assumptions about the distribution of image gray values. Since microtomography was performed on non-sectioned whole mount cells viewed under an 80 kV electron beam, methods of embedment-free specimen preparation with chemical fixation and extraction were employed. These methods were utilized successfully to permit good image formation of the entire cell mitotic nucleus a few micrometers in thickness. The 3D reconstruction of a single kidney cell mitotic nucleus was carried out and shown to produce a reasonable microtomogram of gross features like the condensed chromosomes.

关键词： Algorithms Anaphase Animals Cell Line Cell Nucleus/ultrastructure Chromosomes/ultrastructure image processing, computer-assisted Microscopy, Electron Software Tomography/methods

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HREM STUDY OF IRRADIATION DAMAGE IN HUMAN DENTAL ENAMEL CRYSTALS

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ULTRAMICROSCOPY 1991年第3-4期35卷 305-322页

作者： BRES, EF HUTCHISON, JL SENGER, B VOEGEL, JC FRANK, RM UNIV OXFORD DEPT MAT OXFORD OX1 3PH ENGLAND

Several phenomena have been observed during the examination of human dental enamel crystals (mainly constituted by hydroxyapatite (OHAP)) by high-resolution electron microscopy (HREM) at 300 and 400 keV: orientation-dependent damage in the form of mass loss from voids or uniform destruction of crystal structure, beam-induced diffusion creating outgrowths at the crystal surfaces, recrystallization of the bulk crystal and crystallization of the inorganic components of the matrix surrounding the crystals. These beam-induced crystals have the CaO structure. The phenomena observed are most likely due to various electron-crystal interaction mechanisms (ballistic knock-on damage, electronic excitations, temperature rise, etc.). In this paper, the contribution of the ballistic process to the phenomena observed is discussed. The quantitative description of the knock-on collisions rests on the McKinley-Feshbach cross-section formula. The minimum ion displacement energies which appear in this expression have been estimated on the basis of the electrostatic ion binding energies, and the covalent bond energies if required. It is shown that hydroxyl, calcium and oxygen ions can effectively be displaced by the incident 300 and 400 keV electrons. Thus, the formation of CaO crystals by the combination of calcium and oxygen ions diffusing from their initial sites inside the OHAP lattice can tentatively be explained.

关键词： Adult Calcium/chemistry Calcium Compounds Crystallization Crystallography/methods Dental Enamel/chemistry Dental Enamel/radiation effects Dental Enamel/ultrastructure Durapatite Durapatite Electrons Electrons Hot Temperature Humans Hydroxyapatites/chemistry Hydroxyapatites/chemistry Hydroxyapatites/radiation effects Hydroxyapatites/radiation effects image processing, computer-assisted Microscopy, Electron/methods Middle Aged Oxides/chemistry

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3D RECONSTRUCTION BY COMBINING DATA FROM SECTIONS CUT OBLIQUE TO DIFFERENT UNIT-CELL AXES

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ULTRAMICROSCOPY 1994年第4期55卷 357-371页

作者： WINKLER, H TAYLOR, KA DUKE UNIV MED CTRDEPT CELL BIOLDURHAMNC 27710

Oblique section reconstruction (OSR) can produce a 3D image from a single micrograph of a section through a 2D or 3D crystal. Resolution, however, is limited in a direction perpendicular to the section plane. When data from sections cut at different orientations are combined, the inherent resolution limitation for single sections can be overcome. In the extreme, combination of sections cut oblique to different principal planes of the unit cell can produce a 3D reconstruction with isotropic resolution. The merging of data from different sections requires determination of section thickness and orientation. A method for section thickness determination is described that is generally applicable even to space groups with little or no symmetry. In addition, an approach has been developed to determine rotational orientation within the hexagonal lattice of insect flight muscle. Finally, an iterative least-squares fitting method is applied to determine a 3D set of deconvoluted structure factors from the merged data.

关键词： Adenylyl Imidodiphosphate Animals Crystallography, X-Ray Flight, Animal Flight, Animal Fourier Analysis Fourier Analysis Hemiptera image processing, computer-assisted Microscopy, Electron/methods Muscle, Skeletal/ultrastructure Sarcomeres/ultrastructure

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SPOT-SCAN IMAGING OF MICROCRYSTALS OF AN INFLUENZA NEURAMINIDASE ANTIBODY FRAGMENT-COMPLEX

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ULTRAMICROSCOPY 1991年第2期35卷 131-143页

作者： BULLOUGH, PA TULLOCH, PA MRC MOLEC BIOL LAB CAMBRIDGE CB2 2QH ENGLAND CSIRO DIV BIOMOLEC ENGN PARKVILLE VIC 3052 AUSTRALIA

Electron micrographs of two-dimensional microcrystals of a complex of an avian influenza virus neuraminidase and an antibody Fab fragment, termed 32/3, have been recorded using the spot-scan method of imaging. The crystals have a large unit cell (159.5 angstrom x 159.5 angstrom x 130.5 angstrom) and a high solvent content (approximately 71% by volume) and are a challenging specimen for testing the spot-scan methodology. Crystalline order was preserved to beyond 4 angstrom resolution as demonstrated by electron diffraction, using an embedding medium of a mixture of glucose and neutral potassium phosphotungstate. Using a Philips C400 computer control system interfaced to an EM420 electron microscope, and with the inclusion of additional software in the system, we have been able to record micrographs at low temperature with a relatively narrow (1500 angstrom diameter) moving beam. There is evidence that the use of such a spot-scan beam reduces the effects of beam-induced specimen motion on the quality of micrographs. Conventional low-dose "flood-beam" images showed good isotropic optical diffraction in only 15% of cases whereas 30% of spot-scan images showed good diffraction. The best flood-beam images gave phases to only 15 angstrom resolution after computer processing, whereas the best spot-scan images gave phases to 7 angstrom resolution. Electron diffraction patterns were also recorded at low temperature, and the resulting diffraction amplitudes combined with phases from spot-scan images to yield a projection map of the structure. A 7 angstrom resolution projection map of the complex is presented, and is compared with the projection map of the same avian influenza neuraminidase complexed with a different monoclonal Fab fragment, NC41, which has been solved to high resolution by X-ray diffraction.

关键词： Animals Antibodies, Viral/chemistry Binding Sites Crystallization Crystallography image processing, computer-assisted Immunoglobulin Fab Fragments/chemistry Immunoglobulin Fab Fragments/chemistry Immunoglobulin Fab Fragments/ultrastructure Immunoglobulin Fab Fragments/ultrastructure Influenza A virus/enzymology Influenza A virus/immunology Influenza A virus/ultrastructure Microscopy, Electron Neuraminidase/chemistry Neuraminidase/ultrastructure X-Ray Diffraction

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ELECTRIC BIREFRINGENCE IMAGING OF ELECTROKINETIC AGAROSE ORIENTATION

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BIOPOLYMERS 1991年第9期31卷 1095-1104页

作者： LANAN, M SHICK, R MORRIS, MD Department of Chemistry University of Michigan Ann Arbor Michigan 48109-1055

Time-resolved and steady-state electric birefringence imaging with a slow-scan video camera is used to study orientation during DNA agarose gel electrophoresis. The hydrodynamically induced gel distortion is shown to be the major source of birefringence under electrophoresis running conditions and to generate a birefringence image that approximates the image of the DNA concentration gradient in the electric field direction. A fluid kinematic model is presented to describe the spatial distribution of steady-state birefringence and is verified with fluorescence measurements of DNA distribution. The stress-optic coefficient of 1% agarose gel is measured by mechanical compression and used to evaluate the magnitude of the induced strain on the gel during electrophoresis.

关键词： Birefringence DNA/chemistry DNA/isolation & purification Electrochemistry Electrophoresis, Agar Gel/instrumentation image processing, computer-assisted Kinetics Nucleic Acid Conformation Videotape Recording

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ACETYLCHOLINE-RECEPTOR CHANNEL imageD IN THE OPEN STATE

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NATURE 1995年第6509期373卷 37-43页

作者： UNWIN, N MRC Lab. Mol. Biol. Hills Rd. Cambridge CB2 2QH UK

The structure of the open-channel form of the acetylcholine receptor has been determined from electron images of Torpedo ray postsynaptic membranes activated by brief (<5 ms) mixing with droplets containing acetylcholine. Comparison with the closed-channel form shows that acetylcholine Initiates small rotations of the subunits in the extracellular domain, which trigger a change in configuration of a-helices lining the membrane-spanning pore. The open pore tapers towards the intracellular membrane face, where it is shaped by a 'barrel' of a-helices having a pronounced right-handed twist.

关键词： Acetylcholine Animals Ferritins Freezing image processing, computer-assisted Ion Channel Gating Ions Permeability Receptors, Nicotinic/ultrastructure Receptors, Nicotinic/ultrastructure Synaptic Membranes/ultrastructure Torpedo

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computer quantification of intracellular gold particles

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BIOTECHNIQUES 1999年第3期26卷 494-+页

作者： Bisland, SK Calvieri, B Doyle, B Gariépy, J Univ Toronto Toronto ON Canada Ontario Canc Inst Toronto ON M4X 1K9 Canada

We describe the use of image software programs available for both PC and Macintosh((R)) computers to quantify the accumulation and distribution of gold-labeled constructs within two-dimensional cell sections. The compartmentalization of a biotinylated-peptide was visualized in radiation-induced fibrosarcoma cells by transmission electron microscopy, using a gold particle-streptavidin conjugate. This study illustrates the ease of tabulating gold particles observed in scanned electron micrographs, using Adobe((R)) Photoshop((R)) in conjunction with the public domain NIH image program (Version 1.61). Quantitative information regarding the localization of molecules inside cells is crucial in defining their sites of action and in developing more effective therapeutic agents.

关键词： Animals Biotinylation Fibrosarcoma/chemistry Fibrosarcoma/pathology Fibrosarcoma/ultrastructure Gold/analysis image processing, computer-assisted Microscopy, Electron Tumor Cells, Cultured/chemistry Tumor Cells, Cultured/ultrastructure

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The structure of photosystem II in Arabidopsis:: Localization of the CP26 and CP29 antenna complexes

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BIOCHEMISTRY 2003年第3期42卷 608-613页

作者： Yakushevska, AE Keegstra, W Boekema, EJ Dekker, JP Andersson, J Jansson, S Ruban, AV Horton, P Univ Sheffield Dept Mol Biol & Biotechnol Robert Hill Inst Sheffield S10 2TN S Yorkshire England Univ Groningen Groningen Biomol Sci & Biotechnol Inst NL-9747 AG Groningen Netherlands Free Univ Amsterdam Div Phys & Astron Fac Sci NL-1081 HV Amsterdam Netherlands Umea Univ Dept Plant Physiol Umea Plant Sci Ctr S-90187 Umea Sweden

A genetic approach has been adopted to investigate the organization of the light-harvesting proteins in the photosystem II (PSII) complex in plants. PSII membrane fragments were prepared from wild-type Arabidopis thaliana and plants expressing antisense constructs to Lhcb4 and Lhcb5 genes, lacking CP29 and CP26, respectively (Andersson et al. (2001) Plant Cell 13, 1193-1204). Ordered PSII arrays and PSII supercomplexes were isolated from the membranes of plants lacking CP26 but could not be prepared from those lacking CP29. Membranes and supercomplexes lacking CP26 were less stable than those prepared from the wild type. Transmission electron microscopy aided by single-particle image analysis was applied to the ordered arrays and the isolated PSII complexes. The difference between the images obtained from wild type and antisense plants showed the location of CP26 to be near CP43 and one of the light-harvesting complex trimers. Therefore, the location of the CP26 within PSII was directly established for the first time, and the location of the CP29 complex was determined by elimination. Alterations in the packing of the PSII complexes in the thylakoid membrane also resulted from the absence of CP26. The minor light-harvesting complexes each have a unique location and important roles in the stabilization of the oligomeric PSII structure.

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Continuous class pattern recognition for pathology, with applications to non-Hodgkin's follicular lymphomas

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PATTERN RECOGNITION 1996年第12期29卷 2061-2078页

作者： Firestone, LM Preston, K Nathwani, BN CARNEGIE MELLON UNIV DEPT ELECT ENGN & BIOMED ENGNPITTSBURGHPA 15213 UNIV SO CALIF SCH MEDDEPT PATHOLLOS ANGELESCA

Continuous class pattern recognition is a new analytic method that differs from existing techniques by recognizing and exploiting the continuous relationship among classes along diagnostic scales. Continuous class pattern recognition was applied to a wide variety of image processing features extracted from lymph node biopsy images that were digitized using a Coulter diff3/50 automated research microscope. The resultant classifiers correctly subtyped 89% of a set of 37 follicular lymphomas, compared to individual pathologist rates that ranged from 57% to 81%. This study demonstrates that continuous class pattern recognition can significantly reduce this diagnostic error rate. Copyright (C) 1996 Pattern Recognition Society.

关键词： pattern recognition regression continuous class pattern recognition lymphoma, non-Hodgkin's lymphoma, follicular diagnostic imaging image processing, computer-assisted pathology, clinical

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