Changes in the Proportion and Composition of Structural Proteins during the Development of X-Ray Cataract in Rabbit Lens1

2015 ◽  
pp. 105-118 ◽  
Author(s):  
K. N. Liem-The ◽  
P. J. Ringens ◽  
J. C. W. M. Holtslag ◽  
H. J. Hoenders
Keyword(s):  
Structural Proteins ◽  
X Ray

Pehr Victor Edman, 14 April 1916 - 19 March 1977

1979 ◽  
Vol 25 ◽  
pp. 241-265 ◽  
Keyword(s):  
Spatial Configuration ◽  
Structural Proteins ◽  
Evolutionary Relationships ◽  
Protein Chemistry ◽  
X Ray Diffraction ◽  
Essential Information ◽  
X Ray ◽  
Automated Method ◽  
Colloid Science

Pehr Edman died after a short illness at the age of 60 in Munich. His untimely death brought to an end a long and challenging undertaking which although not quite finished to his own satisfaction has brought about a revolution in protein chemistry. Edman’s work has provided chemists with a capability undreamt of a generation ago: the power to determine the amino acid sequence of long runs of peptide chain with speed and precision by an automated method. This has put into man’s grasp essential information for the study of the genetic replication of enzymes and structural proteins and has completed the graduation of protein chemistry from a branch of colloid science to a fundamental organ of molecular genetics. It now seems scarcely necessary to say that the sequencing of proteins, combined with X-ray diffraction analysis, provides a powerful tool to aid the determination of their complete spatial configuration including that of the interface with solvent which carries most of the biological activity. Extension of knowledge of protein sequences is essential in the search for evolutionary relationships between different proteins. In addition, studies of numerous heritable diseases are now showing how aberrant enzymes and structural proteins produced by genetic errors affecting the primary sequence may give rise to the malfunctions observed and how this exact knowledge may sometimes be used to alleviate the condition.

scholarly journals Raman spectroscopy of fingernails: A novel tool for evaluation of bone quality?

2010 ◽  
Vol 24 (5) ◽  
pp. 517-524 ◽  
Author(s):  
N. M. Cummins ◽  
J. C. C. Day ◽  
A. Wren ◽  
P. Carroll ◽  
N. Murphy ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Bone Quality ◽  
Bone Remodelling ◽  
Dual Energy ◽  
Structural Proteins ◽  
Spectral Features ◽  
Mineral Density ◽  
X Ray ◽  
Large Populations ◽  
History Of

Raman data from human fingernails has been analysed to determine if a relationship exists between spectral features and bone quality. Previous work demonstrated a relationship between the manually determined intensity of the disulphide peak (Bone Quality Test; BQT) and osteoporotic fracture. A computer program is now described that automates the BQT determination for large sample-sets. In this study the ability of the automated BQT to discriminate between fractures and controls was compared to that of bone mineral density (BMD) and biomarkers of bone remodelling. Females aged 18–67 years participated in the study (n═ 159). Fingernails were analysed using Raman spectroscopy. Lumbar and Femoral BMD was measured by dual energy X-ray absorptiometry (DXA). Fasting venepuncture samples were analysed for osteocalcin and CTx (collagen C-telopeptides) by electrochemiluminescence. No correlation was found between the BQT and BMD or the biomarkers. The BQT and BMD were found to be equally accurate in identifying subjects with a history of fracture (p< 0.01) and both outperformed osteocalcin and CTx. It appears that keratin and collagen are related structural proteins that require disulphide bonding for stability. Therefore, these preliminary results suggest that Raman spectroscopy of keratin may have potential as a diagnostic tool for screening bone quality in large populations.

HAp Protein Composites Formed by Hydrolysis of α-TCP

2005 ◽  
Vol 284-286 ◽  
pp. 39-42 ◽  
Author(s):  
Ahmed H. Touny ◽  
Paul W. Brown
Keyword(s):  
Type I Collagen ◽  
Isothermal Calorimetry ◽  
Protein Structures ◽  
Structural Proteins ◽  
Surrounding Tissue ◽  
Type I ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hydrolysis Of ◽  
Aggressive Effect

Composite material composed of hydroxyapatite (HAp) and structural proteins, such as type I collagen or cross-linked gelatins, were synthesized at 37.4°C by hydrolysis of alpha tricalcium phosphate (α-TCP) in the presence of these protein structures. X-ray diffraction (XRD)and isothermal calorimetry were used as tools to evaluate the rate of HAp formation. Rates of HAp formation depend on protein structure. Gelatin enhances HAp formation while collagen delays it. Changes in pH during the hydrolysis α-TCP are unlikely to have an aggressive effect on the surrounding tissue. The presence of the protein improves the ductility of the HAp/protein composite but it decreases the tensile strength.

scholarly journals Crystal Structure of a Virus-Encoded Putative Glycosyltransferase

2010 ◽  
Vol 84 (23) ◽  
pp. 12265-12273 ◽  
Author(s):  
Ye Xiang ◽  
Ulrich Baxa ◽  
Ying Zhang ◽  
Alasdair C. Steven ◽  
Gentry L. Lewis ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Gene Product ◽  
Isothermal Titration Calorimetry ◽  
Active Form ◽  
Structural Proteins ◽  
Titration Calorimetry ◽  
Type B ◽  
Active Centers ◽  
X Ray ◽  
X Ray Crystallography

ABSTRACT The chloroviruses (family Phycodnaviridae), unlike most viruses, encode some, if not most, of the enzymes involved in the glycosylation of their structural proteins. Annotation of the gene product B736L from chlorovirus NY-2A suggests that it is a glycosyltransferase. The structure of the recombinantly expressed B736L protein was determined by X-ray crystallography to 2.3-Å resolution, and the protein was shown to have two nucleotide-binding folds like other glycosyltransferase type B enzymes. This is the second structure of a chlorovirus-encoded glycosyltransferase and the first structure of a chlorovirus type B enzyme to be determined. B736L is a retaining enzyme and belongs to glycosyltransferase family 4. The donor substrate was identified as GDP-mannose by isothermal titration calorimetry and was shown to bind into the cleft between the two domains in the protein. The active form of the enzyme is probably a dimer in which the active centers are separated by about 40 Å.

Space and Time Distribution of Hard X-Ray Emission in a Loop at the Beginning of a Flare

1994 ◽  
Vol 144 ◽  
pp. 275-277
Author(s):  
M. Karlický ◽  
J. C. Hénoux
Keyword(s):  
Time Distribution ◽  
Electron Bombardment ◽  
Spatial Evolution ◽  
Superthermal Electrons ◽  
Flare Loop ◽  
X Ray ◽  
Superthermal Electron ◽  
Flare Loops ◽  
Chromospheric Evaporation ◽  
Temporal And Spatial

AbstractUsing a new ID hybrid model of the electron bombardment in flare loops, we study not only the evolution of densities, plasma velocities and temperatures in the loop, but also the temporal and spatial evolution of hard X-ray emission. In the present paper a continuous bombardment by electrons isotropically accelerated at the top of flare loop with a power-law injection distribution function is considered. The computations include the effects of the return-current that reduces significantly the depth of the chromospheric layer which is evaporated. The present modelling is made with superthermal electron parameters corresponding to the classical resistivity regime for an input energy flux of superthermal electrons of 109erg cm−2s−1. It was found that due to the electron bombardment the two chromospheric evaporation waves are generated at both feet of the loop and they propagate up to the top, where they collide and cause temporary density and hard X-ray enhancements.

Some Problems in Understanding the Solar Corona

1994 ◽  
Vol 144 ◽  
pp. 1-9
Author(s):  
A. H. Gabriel
Keyword(s):  
Solar Corona ◽  
Solar Atmosphere ◽  
Theoretical Modelling ◽  
Total System ◽  
Major Advance ◽  
X Ray ◽  
Proper Perspective ◽  
Space Observations

The development of the physics of the solar atmosphere during the last 50 years has been greatly influenced by the increasing capability of observations made from space. Access to images and spectra of the hotter plasma in the UV, XUV and X-ray regions provided a major advance over the few coronal forbidden lines seen in the visible and enabled the cooler chromospheric and photospheric plasma to be seen in its proper perspective, as part of a total system. In this way space observations have stimulated new and important advances, not only in space but also in ground-based observations and theoretical modelling, so that today we find a well-balanced harmony between the three techniques.

White-Light Coronal Structures: Streamers and CMEs

1994 ◽  
Vol 144 ◽  
pp. 82
Author(s):  
E. Hildner
Keyword(s):  
Emission Line ◽  
Electron Density ◽  
White Light ◽  
Coronal Mass Ejections ◽  
X Rays ◽  
Solar Cycles ◽  
Temperature Function ◽  
X Ray ◽  
Eclipse Observations ◽  
Coronal Structures

AbstractOver the last twenty years, orbiting coronagraphs have vastly increased the amount of observational material for the whitelight corona. Spanning almost two solar cycles, and augmented by ground-based K-coronameter, emission-line, and eclipse observations, these data allow us to assess,inter alia: the typical and atypical behavior of the corona; how the corona evolves on time scales from minutes to a decade; and (in some respects) the relation between photospheric, coronal, and interplanetary features. This talk will review recent results on these three topics. A remark or two will attempt to relate the whitelight corona between 1.5 and 6 R⊙to the corona seen at lower altitudes in soft X-rays (e.g., with Yohkoh). The whitelight emission depends only on integrated electron density independent of temperature, whereas the soft X-ray emission depends upon the integral of electron density squared times a temperature function. The properties of coronal mass ejections (CMEs) will be reviewed briefly and their relationships to other solar and interplanetary phenomena will be noted.

Iron K-Line Emission from X-Ray Binaries

1988 ◽  
Vol 102 ◽  
pp. 47-50
Author(s):  
K. Masai ◽  
S. Hayakawa ◽  
F. Nagase
Keyword(s):  
Accretion Disk ◽  
Radiative Recombination ◽  
Characteristic Temperature ◽  
Line Emission ◽  
Ionization Front ◽  
Continuum Radiation ◽  
X Ray ◽  
Low Mass ◽  
X Ray Binaries

AbstractEmission mechanisms of the iron Kα-lines in X-ray binaries are discussed in relation with the characteristic temperature Txof continuum radiation thereof. The 6.7 keV line is ascribed to radiative recombination followed by cascades in a corona of ∼ 100 eV formed above the accretion disk. This mechanism is attained for Tx≲ 10 keV as observed for low mass X-ray binaries. The 6.4 keV line observed for binary X-ray pulsars with Tx&gt; 10 keV is likely due to fluorescence outside the He II ionization front.

Diagnostics of Gold Laser Plasmas

1988 ◽  
Vol 102 ◽  
pp. 357-360
Author(s):  
J.C. Gauthier ◽  
J.P. Geindre ◽  
P. Monier ◽  
C. Chenais-Popovics ◽  
N. Tragin ◽  
...  
Keyword(s):  
Experimental Results ◽  
Pure Gold ◽  
Electronic Temperature ◽  
X Ray ◽  
Laser Plasmas ◽  
Collisional Radiative Model ◽  
Radiative Model

AbstractIn order to achieve a nickel-like X ray laser scheme we need a tool to determine the parameters which characterise the high-Z plasma. The aim of this work is to study gold laser plasmas and to compare experimental results to a collisional-radiative model which describes nickel-like ions. The electronic temperature and density are measured by the emission of an aluminium tracer. They are compared to the predictions of the nickel-like model for pure gold. The results show that the density and temperature can be estimated in a pure gold plasma.

Axial Observation of X-Ray Spectra from a Beam-Foil Source

1988 ◽  
Vol 102 ◽  
pp. 339-342
Author(s):  
J.M. Laming ◽  
J.D. Silver ◽  
R. Barnsley ◽  
J. Dunn ◽  
K.D. Evans ◽  
...  
Keyword(s):  
Spectral Resolution ◽  
Heavy Ion ◽  
Ion Beams ◽  
Beam Axis ◽  
Doppler Broadening ◽  
X Ray ◽  
Beam Foil

AbstractNew observations of x-ray spectra from foil-excited heavy ion beams are reported. By observing the target in a direction along the beam axis, an improvement in spectral resolution, δλ/λ, by about a factor of two is achieved, due to the reduced Doppler broadening in this geometry.

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