Arne Engström

A method for the determination of the mass of extremely small biological objects

Abstract A method for the determination of the mass of as small biological objects as single cell structures is described. The method is based upon absorption measurements of soft filtered continuous x-rays. From adsorption data the mass can be calculated. The complete theory of the method is given. An x-ray equipment for the mass determination has been constructed and is described in detail. A number of biological applications are presented.

The low-angle scatter of X-rays from bone tissue

Abstract A study has been made of the diffuse low-angle X-ray scatter from a number of longitudinal and cross-sections of normal intact bone. From considerations of the variations of intensity of scatter from well-oriented specimens, the size and shape of the scattering particles have been deduced. In intact human bone, the scattering particles appear to be of uniform size and to approximate to rods which have a diameter of about 75 A and are about 210 A long. The particles appear to be well-aligned, with their long axes in the direction of the longitudinal axis of the bone and parallel to the collagen fibre axis. Particles from other types of normal bone seem to be of a similar shape and size.

Electron microscopy and x-ray diffraction of bone.

Abstract Evidence derived from X-ray crystallographic and polarized light studies point to the existence of rod-or needle-shaped apatite particles in bone. From low-angle X-ray scattering studies and from measurements of the profiles of the wide-angle X-ray lines a particle diameter of about 50 A was derived. The application of the diamond knife to the sectioning of intact bone has made it possible to obtain ultra-thin sections of bone tissue, suitable for electron microscopy. The electron micrography indicated that the apatite particles are needle-shaped, 30–60 A in diameter and aligned along the collagen matrix.

Lamellar structure of osteons demonstrated by microradiography.

Die Lamellen des Haverschen Systems wurden durch Röntgenmikroradiographie demonstriert. Lamellen mit hoher Röntgenabsorption wechseln mit solchen niedriger Absorption ab.

Renewal of phosphate in bone minerals. II. Radioautographic studies of the renewal of phosphate in different structures of bone.

Abstract 1. 1. Labelled phosphate, when injected intravenously, is unevenly distributed in bone tissue. 2. 2. Radioautographic and microradiographic examinations have shown that young Haversian systems have the highest uptake of radioactive phosphate. When a system becomes older and the amount of mineral salts approaches a maximum value the uptake of radioactive phosphate becomes very low. 3. 3. The main reason for the rapid initial uptake of labelled phosphate cannot be the occurrence of surface reactions throughout the whole bone tissue.

Biophysical Studies on Bone Tissue III. Osteopetrosis (Marble Bone Disease)

Summary

I. Microradiography: A Review*

Various types of microradiography are treated in this survey. The resolution possible is about 0·5 μ in ideal cases. Quantitative microradiography with monochromatic X rays permits certain histo-chemical elementary analysis. Utilising very soft X rays it is possible to determine the dry weight of cellular structures. The applications of microradiography to the study of the degree of mineralisation in calcified tissues is discussed in detail. The use of microangiography in demonstrating the finest blood vessels, microangiography, as well as a short survey of X-ray microdiffraction techniques are discussed.

Relation between collagen and mineral salts in bone tissue

Bei Ablagerung von Hydroxylapatit in kollagenen Fasern des Knochengewebes können diese zur Orientierung der anorganischen Moleküle führen.

Low angle reflection in X-ray diffraction patterns of bone tissue

Es konnten Kleinwinkel-Röntgenbeugungen an Diffraktionsbildern von dekollagenisiertem Fischknochen beobachtet werden. Diese Beugungen können vollständig zu der Partikelgrösse in der kontinuierlichen Kleinwinkelbeugung weniger geordneter Systeme in Beziehung gesetzt werden. Die Ergebnisse betonen die nahe Verwandtschaft zwischen der Grösse der Apatit-Partikel und der periodischen Struktur des Kollagens.

X-RAY MICROSCOPY, PAST, PRESENT, AND FUTURE

My first contact with x-rays and x-ray imaging was when I was eight years old (1928). I was buying a pair of new shoes. The shop had advertised that the buyer could check the position of his foot in the shoe with an x-ray fluoroscope. It was fascinating. However, the low sensitivity of the x-ray screens available at that time, together with the long time that children spent gazing at their foot skeleton, meant that they must have been exposed to radiation doses that would horrify present-day radiation protection agencies. Anyway, my interest in the magic of x-rays was aroused. Later, at school, I tried to get hold of some literature on x-rays and, after learning foreign languages, the first scientific text on x-rays I read was a book published (as early as 1912) by the famous German physicist Robert Pohl, Die Physik der Rontgenstrahlen. The book is signed Gliicksburg-Ostsee, August 1912. The preface is particularly interesting, since it marks, in its way, a new era in the scientific investigation into the real nature of matter by means of x-rays. What was under intense discussion at that time was the “Impulsbreite” of x-rays and their eventual wave characteristics and, therefore, an addendum to the book is justified in the following way: “Nach Vollendung des Manusciptes erfuhr ich von den Versuchen der Herren h u e , Friedrich und Knipping und die Freundlichkeit dieser Herren ermoglichte es mir als Nachtrag ein besonderes Kapital iiber die Interferenz erscheinungen anzufangen die in vielfacher Hinsicht von grundlegender Bedeutung sin#’.* In a pointed commentary, Pohl, as an exponent of the German school, says that he had omitted Bragg’s corpuscular theory of x-rays from his text since he could see no way in which this theory could explain the properties of x-rays. It may seem somewhat unusual, mentioning this little-known book, but, together with Rontgen’s masterly original papers and Compton and Allison’s unsurpassed textbook on x-rays in theory and practice, it has been my basic x-ray university. Imaging with x-rays in the scale 1: 1 advanced technically in the period between the two world wars and found increased use and applications. Scattered attempts were made to image objects with still greater sharpness, especially in the fields of metallurgy and mineralogy, but also in medical radiography. One could classify these attempts as general physical experimentation to improve the sharpness and resolution of x-ray images, a struggle between sharpness and dose rate. Naturally, x-ray microscopy was thought and dreamt of, especially the high resolving power possible, in theory, because of the short wavelengths of x-rays compared with those of visible light. This was discussed in the late ’thirties by the German physicist Manfred von Ardenne in his book on electron microscopy, which, though physically valid, consisted mainly of ideas and paper constructions.