scholarly journals DEVELOPMENT OF FEATHER KERATIN DURING EMBRYOGENESIS OF THE CHICK

1963 ◽  
Vol 16 (2) ◽  
pp. 215-223 ◽  
Author(s):  
Eugene Bell ◽  
Y. T. Thathachari
Keyword(s):  
Lipid Extraction ◽  
Embryonic Chick ◽  
Tissue Architecture ◽  
X Ray Diffraction ◽  
X Ray ◽  
Adult Pattern ◽  
Equatorial Reflection ◽  
Cross Links ◽  
Meridional Reflection ◽  
Basic Features

The development of keratin in 9 to 17 day embryonic chick feathers has been studied by x-ray diffraction and cytochemical methods. The x-ray diffraction pattern given by the 9-day feathers contains none of the features seen in the adult pattern. In the 10 to 11 day patterns, besides two diffuse rings centered at 4.7 A and 10 A, two sharp, rather weak rings are seen at 35 A and 4.2 A with slight preferred orientations about the equator and the meridian, respectively. At 12 days, in addition to the foregoing, a sharp intense equatorial reflection at ∼56 A is observed. On treatment with lipid solvents, the 35 A ring is removed; prolonged extraction removes the 4.2 A ring, while blurring the 56 A reflection and enhancing the central low angle scatter. The 14-day pattern shows, besides all the features seen in the earlier patterns, a 23 A meridional reflection and other meridional and near meridional reflections. All the basic features of the adult pattern are seen at this stage and remain essentially intact on lipid extraction. Beyond 14 days, the pattern remains essentially the same, only improving in clarity and detail. The 4.2 A ring seen in the 10 to 15 day pattern is scarcely detectable in the 16-day pattern. Cytochemical evidence indicates that extensive —S—S bond formation occurs between the 13th and 14th days. It is suggested that lipids serve as a framework for the developing keratin structure which acquires permanent stability through hydrogen bonds and disulfide cross-links. The relation between keratin synthesis and tissue architecture as well as cytodifferentiation is discussed.

Failure to detect crystalline brushite in embryonic chick and bovine bone by X-ray diffraction

1984 ◽  
Vol 86 (1) ◽  
pp. 93-99 ◽  
Author(s):  
Laurence C. Bonar ◽  
Marc D. Grynpas ◽  
Melvin J. Glimcher
Keyword(s):  
Bovine Bone ◽  
Embryonic Chick ◽  
X Ray Diffraction ◽  
X Ray

A curved image-plate detector system for high-resolution synchrotron X-ray diffraction

2009 ◽  
Vol 16 (2) ◽  
pp. 273-282 ◽  
Author(s):  
P. Sarin ◽  
R. P. Haggerty ◽  
W. Yoon ◽  
M. Knapp ◽  
A. Berghaeuser ◽  
...  
Keyword(s):  
High Resolution ◽  
Materials Science ◽  
Photon Flux ◽  
Detector Response ◽  
X Ray Diffraction ◽  
X Ray ◽  
Image Plate ◽  
Intensity Information ◽  
High Temperature Xrd ◽  
Basic Features

The developed curved image plate (CIP) is a one-dimensional detector which simultaneously records high-resolution X-ray diffraction (XRD) patterns over a 38.7° 2θ range. In addition, an on-site reader enables rapid extraction, transfer and storage of X-ray intensity information in ≤30 s, and further qualifies this detector to study kinetic processes in materials science. The CIP detector can detect and store X-ray intensity information linearly proportional to the incident photon flux over a dynamical range of about five orders of magnitude. The linearity and uniformity of the CIP detector response is not compromised in the unsaturated regions of the image plate, regardless of saturation in another region. The speed of XRD data acquisition together with excellent resolution afforded by the CIP detector is unique and opens up wide possibilities in materials research accessible through X-ray diffraction. This article presents details of the basic features, operation and performance of the CIP detector along with some examples of applications, including high-temperature XRD.

Some Low-Angle X-Ray Evidence on the Structural Changes in Thermally- and Plasma-Treated Wool

1976 ◽  
Vol 46 (11) ◽  
pp. 779-785 ◽  
Author(s):  
Kay Sue Lee
Keyword(s):  
Diffraction Pattern ◽  
Structural Changes ◽  
Azimuthal Angle ◽  
Prolonged Treatment ◽  
X Ray Diffraction ◽  
X Ray ◽  
Heat Resistant ◽  
Diffraction Patterns ◽  
Meridional Reflection ◽  
Thermally Treated

A series of events occurred when wool was heated in vacuum. At some stages structural changes in the thermally-treated wool were observed, as reflected in the low-angle x-ray diffraction patterns. An increase in the intensity of the 39 Å meridional reflection and the appearance of a 4-point diagram with azimuthal angle of 45° at about 46 Å spacing were observed when wool was heated near 170°C for 90 min. Similar results were found in samples heated at higher temperatures but for shorter time. The most heat-resistant meridional reflection is the 66 Å. The low-angle x-ray diffraction patterns of plasma-treated wool showed only disappearance of the sharp lipid ring at 48 Å. No intensification of any reflection was observed. Prolonged treatment with plasma destroys the low-angle x-ray diffraction pattern of wool.

scholarly journals Frog skeletal muscle thick filaments are three-stranded.

1983 ◽  
Vol 96 (6) ◽  
pp. 1797-1802 ◽  
Author(s):  
R W Kensler ◽  
M Stewart
Keyword(s):  
Skeletal Muscle ◽  
Optical Diffraction ◽  
Layer Line ◽  
X Ray Diffraction ◽  
Computer Image Analysis ◽  
X Ray ◽  
Thick Filaments ◽  
Diffraction Patterns ◽  
Meridional Reflection ◽  
Vertebrate Skeletal Muscle

A procedure has been developed for isolating and negatively staining vertebrate skeletal muscle thick filaments that preserves the arrangement of the myosin crossbridges. Electron micrographs of these filaments showed a clear periodicity associated with crossbridges with an axial repeat of 42.9 nm. Optical diffraction patterns of these images showed clear layer lines and were qualitatively similar to published x-ray diffraction patterns, except that the 1/14.3-nm meridional reflection was somewhat weaker. Computer image analysis of negatively stained images of these filaments has enabled the number of strands to be established unequivocally. Both reconstructed images from layer line data and analysis of the phases of the inner maxima of the first layer line are consistent only with a three-stranded structure and cannot be reconciled with either two- or four-stranded models.

Abstract P350: Myofibril Orientation In Cardiac Muscle And Its Implication For Heart Disease

2021 ◽  
Vol 129 (Suppl_1) ◽  
Author(s):  
Weikang Ma ◽  
Henry Gong ◽  
Vivek Jani ◽  
Maicon Landim-Vieira ◽  
Maria Papadaki ◽  
...  
Keyword(s):  
Cardiac Muscle ◽  
Sampling Error ◽  
Wildtype Mouse ◽  
X Ray Diffraction ◽  
Human Heart Failure ◽  
X Ray ◽  
Equatorial Reflection ◽  
Health And Disease ◽  
Histological Processing ◽  
Diffraction Patterns

Rationale: Myocyte disarray is a hallmark of cardiomyopathy. However, the orientation of individual myofibrils and myofilaments and how their alignment may be altered in disease progression have been largely underexplored. This oversight has been predominantly due to a paucity of methods for objective and quantitative analysis. Objective: To introduce a novel, less-biased approach to quantify myofibrillar and myofilament orientation in cardiac muscle under near physiological conditions and demonstrate its superiority versus traditional histological assessments. Methods and Results: Using small-angle X-ray diffraction, we first investigated changes in myofibrillar orientation at increasing sarcomere lengths in skinned, relaxed, wildtype mouse myocardium by assessing the angular spread of the 1,0 equatorial reflection (angle σ). At a sarcomere length (SL) of 1.9 μm, the angle σ was 0.23±0.01 rad, decreased to 0.19±0.01 rad at a SL of 2.1 μm, and further decreased to 0.15±0.01 rad at a SL of 2.3 μm (p<0.0001). Angle σ was significantly larger in R403Q (a MYH7 HCM model) porcine myocardium (0.24±0.01 rad) compared to WT myocardium (0.14±0.005 rad, p<0.0001) as well as in biopsied human heart failure tissue (0.19±0.006 rad) when compared to non-failing samples (0.17±0.007 rad, p=0.01). These data indicate that diseased myocardium suffers from myofibrillar disorientation compared to healthy controls. Finally, using control samples, we showed that traditional, histological-based analysis of disarray can be subject to user bias and/or sampling error and lead to false positives. Conclusions: Our method for assessing myofibrillar orientation limits the artifacts introduced by traditional histological processing and provides a precise and objective metric for phenotypically characterizing myocardium. The ability to obtain excellent X-ray diffraction patterns from frozen, biopsied human myocardium opens up new avenues of inquiry regarding the relation of myofibrillar structure to function in health and disease.

scholarly journals The Crossbridge Mechanism of Muscular Contraction and its Implications

1985 ◽  
Vol 115 (1) ◽  
pp. 17-30
Author(s):  
H. E. HUXLEY
Keyword(s):  
Electron Microscope ◽  
Muscular Contraction ◽  
Activation Mechanism ◽  
Striated Muscles ◽  
X Ray Diffraction ◽  
X Ray ◽  
Crossbridge Cycle ◽  
Contraction Mechanism ◽  
Basic Features ◽  
Many Sources

The basic features of the sliding-filament crossbridge mechanism are reviewed briefly, and some recent objections involving supposed changes in A-filament lengths are discussed. X-ray diffraction studies on live muscles show no sign of a decrease in axial spacing during contraction, and it is unlikely that a stepwise shortening or depolymerization of A-filaments would provide a plausible contraction mechanism. Thus electron microscope observations which occasionally are reported to show such length changesprobably arise from experimental artefact, of which there are many sources. The factors which govern tension and speed in muscle contraction are described. Since all vertebrate striated muscles which have been studied have A-bands of at least approximately the same length, they are likely to have rather similar maximum isometric tensions. The design probably matches this tension to the strength of the filaments themselves. The large variations in shortening speeds between different muscles and different animals arise because of corresponding variations in the rates of particular steps in the crossbridge cycle and in the rate of ATP splitting by the actin-myosin complex involved. Questions concerning the nature and the speed of the activation mechanism are also discussed.

scholarly journals Myofibril orientation as a metric for characterizing heart disease

2021 ◽  
Author(s):  
Weikang Ma ◽  
Henry Gong ◽  
Vivek Jani ◽  
Maicon Landim-Vieira ◽  
Maria Papadaki ◽  
...  
Keyword(s):  
Sarcomere Length ◽  
Sampling Error ◽  
Wildtype Mouse ◽  
X Ray Diffraction ◽  
Human Heart Failure ◽  
X Ray ◽  
Equatorial Reflection ◽  
Conventional Histology ◽  
Diffraction Patterns ◽  
The Relationship

Myocyte disarray is a hallmark of cardiomyopathy. However, the relationship between alterations in the orientation of individual myofibrils and myofilaments to disease progression has been largely underexplored. This oversight has predominantly been due to a paucity of methods for objective and quantitative analysis. Here we introduce a novel, less-biased approach to quantify myofibrillar and myofilament orientation in cardiac muscle under near physiological conditions and demonstrate its superiority as compared to conventional histological assessments. Using small-angle X-ray diffraction, we first investigated changes in myofibrillar orientation at increasing sarcomere lengths in permeabilized, relaxed, wildtype mouse myocardium by assessing the angular spread of the 1,0 equatorial reflection (angle sigma). At a sarcomere length (SL) of 1.9 microns, the angle sigma was 0.23 +/- 0.01 rad, decreased to 0.19 +/- 0.01 rad at a SL of 2.1 microns, and further decreased to 0.15 +/- 0.01 rad at a SL of 2.3 microns (p<0.0001). Angle sigma was significantly larger in R403Q (a MYH7 HCM model) porcine myocardium (0.24 +/- 0.01 rad) compared to WT myocardium (0.14 +/- 0.005 rad, p<0.0001) as well as in human heart failure tissue (0.19 +/- 0.006 rad) when compared to non-failing samples (0.17 +/- 0.007 rad, p=0.01). These data indicate that diseased myocardium suffers from greater myofibrillar disorientation compared to healthy controls. Finally, we showed that conventional, histology-based analysis of disarray can be subject to user bias and/or sampling error and lead to false positives. Our method for directly assessing myofibrillar orientation avoids the artifacts introduced by conventional histological methods that directly assess myocyte orientation and only indirectly assess myofibrillar orientation, and provides a precise and objective metric for phenotypically characterizing myocardium. The ability to obtain excellent X-ray diffraction patterns from frozen human myocardium provides a new tool for investigating the structural bases of cardiomyopathies.

The Use of Advanced Analytical Techniques for Characterization of the Chemical, Physical, and Crystallographic Nature of a Surface

1973 ◽  
Vol 31 ◽  
pp. 132-133 ◽  
Author(s):  
R. E. Herfert
Keyword(s):  
Surface Characterization ◽  
Analytical Techniques ◽  
X Ray Diffraction ◽  
Depth Of Penetration ◽  
X Ray ◽  
The Past ◽  
Transmission Electron ◽  
Scanning Electron

Studies of the nature of a surface, either metallic or nonmetallic, in the past, have been limited to the instrumentation available for these measurements. In the past, optical microscopy, replica transmission electron microscopy, electron or X-ray diffraction and optical or X-ray spectroscopy have provided the means of surface characterization. Actually, some of these techniques are not purely surface; the depth of penetration may be a few thousands of an inch. Within the last five years, instrumentation has been made available which now makes it practical for use to study the outer few 100A of layers and characterize it completely from a chemical, physical, and crystallographic standpoint. The scanning electron microscope (SEM) provides a means of viewing the surface of a material in situ to magnifications as high as 250,000X.

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