[Comparative studies on amino acids in blood proteins, liver protein, amyloid, hyalin and collagen]

Vergleichende Untersuchungen über das Amyloid und Paramyloid verschiedener Tierarten

The histochemical attributes of amyloid and paramyloid deposits were investigated and compared, using material from cattle, dogs, mink and horses. Histochemically, there is considerable similarity between amyloid and paramyloid. Both are built from a neuraminic acid and carbohydrate-containing protein (glycoprotein), but their neuraminic acid and carbohydrate contents vary considerably in the individual varieties of amyloid. The fibrin-positive substances demonstrable in paramyloid are an indication that blood proteins are incorporated in this variety of amyloid in larger amounts than in ordinary amyloid.

[Comparative studies on the histochemical behavior of amyloid, fibrinoid and hyalin precipitates in the walls of blood vessels of various mammals and birds. 1. Proteins]

Zusammenfassung

In den untersuchten amyloiden, fibrinoiden und hyalinen Gefässwandablagerungen konnten in wechselnder Intensität primäre Aminogruppen, Sulfhydryl- und Disulfidgruppen sowie die Aminosäuren Tryptophan, Tyrosin und Arginin histochemisch dargestellt werden. Da Tryptophan, Tyrosin und Cystin/Cystein verhaltnismassig reichlich in den Plasmaproteinen vorkommen, ist anzunehmen, dass Bluteiweisskörper einen wesentlichen Bestandteil dieser Ablagerungen darstellen. Eine morphologische Unterscheidung des Amyloids, Fibrinoids und Hyalins kann auf Grund des qualitativ-histochemischen Nachweises dieser Aminosäuren nicht vorgenommen werden, weil sie in allen 3 Substraten vorkommen. ∗

The characterization of soluble amyloid prepared in water

Amyloid was extracted from the spleen of a patient with primary amyloidosis by homogenizing it at high speed with water after preliminary treatments, first to remove proteins soluble in saline, and then to remove salts. The extracts containing amyloid appeared to be clear at concentrations up to 6 mg/ml of protein. The material gave little sediment on being centrifuged up to 20,000 g for 1 hr, but the protein was sedimented at 100,000 g in 1 hr. The amyloid could be precipitated from the extracts by addition of NaCl to 0.0075 mole/liter or of CaCl(2) to 0.0025 mole/liter. The protein-bound Congo red formed a red precipitate and this property was used to estimate recovery and purity of amyloid during extraction. On electronmicroscopy the isolated amyloid proved to be morphologically pure. It existed either as single filaments measuring 60-80 A in diameter or as large aggregates of these filaments.Freshly isolated amyloid in water sedimented as a single homogeneous peak with an s degrees (20,[unk]) of about 45-50S. On standing, the solution became cloudy and more rapidly sedimenting components appeared. On electrophoresis the material migrated as a homogeneous peak towards the anode. The protein had an amino acid composition different from that of all known serum proteins. It was rich in acidic amino acids and had little cysteine and methionine and no hydroxyproline. The total content of carbohydrate was less than 2%.

Alterations in serum globulins during the formation and resorption of amyloid in rabbits

A marked increase of the serum beta globulins was found in rabbits developing amyloidosis as a result of prolonged treatment with ribonucleate administered by subcutaneous injections. Following cessation of treatment the beta globulin levels gradually returned to normal while the gamma globulin levels rose strikingly, the changes being accompanied by a resorption of amyloid from the spleen, and probably also from the kidneys. Electrophoretic studies provided some evidence that the increase in beta globulins which accompanied the development of amyloidosis resulted from the production of a globulin not normally present in rabbit serum. A protein or protein derivative that moved as a beta globulin when subjected to filter paper electrophoresis was excreted in substantial quantities in the urine of several amyloidotic rabbits, along with much smaller quantities of substances moving as albumin, alpha and gamma globulins. Considered as a whole, the findings indicate a causal relationship between the abnormal production of circulating beta globulins and the deposition of amyloid in rabbits treated with ribonucleate. Hence it appears that a beta globulin may be directly involved in the formation of amyloid under the conditions of the experiments here reported.