Body weight,metabolic rate,and trace substance turnover in animals

Summary Consequences of size-dependent metabolic rate on the turnover of trace substances in animals are investigated. At steady state, the biological half-life, body burden, and whole body concentration of a trace substance are shown to be proportional to body weight raised to (1-b), 1, and 0, respectively, where b is the exponent relating body weight to standard metabolic rate. The condition is that the trace substance is turned over in proportion to the standard metabolic rate; the derived equations can accordingly be used to test whether a given substance is feasible as a tracer of energy flow in ecologic systems.     

Activity of antioxidants in serum of animals with experimental crush syndrome]

Ischemia of soft tissues in crush syndrome results in activation of free radical oxidation processes, which negatively effect the functions of many biological systems. The presence of antioxidant system in the body can inhibit the action of free radicals. Antiradical effect of this system is seen in vitamin K, ubiquinone and ascorbic acid. The results of the experiment showed that the quantity of vitamin K, ubiquinone and ascorbic acid increases in the serum of blood after decompression of soft tissues in 14 hours, three and seven days. This fact supports an active participation of antioxidant system in the pathogenesis of crush syndrome.     

Acetylcholinesterase molecular forms in serum and erythrocytes of laboratory animals

The distribution of the molecular forms of acetylcholinesterase in the blood of various animal species was examined. The globular tetrameric form was most frequently observed in serum but mouse serum also contained a globular monomer. Globular monomers (rat) dimers (mouse, dog, rabbit) and tetramers (dog) were found in erythrocytes. Interspecies differences make it difficult to formulate a cohesive theory as to the origin and function of blood-borne enzymes.     

Changes in the concentration of serum fibronectin in irradiated animals

A study of the level of fibronectin in blood serum of Wistar rats at different times after gamma-irradiation (7.5 Gy) has demonstrated a considerable increase in its concentration after 3 days. This increase is a function of radiation dose absorbed (within the range from 1 to 10 Gy). The most pronounced changes are observed with serious and extremely serious forms of acute radiation sickness. The administration of cycloheximide 48 h after irradiation removes completely the increase in the level of blood serum fibronectin.     

Blood serum proteins and the mineralization of bone ground substance

Summary Direct tracing experiments with fluorochrome-labeled homologous blood serum show that certain serum components are taken up by the bone substance of young and adult rats. These proteins are concentrated and incorporated into the organic matrix while it is being formed. They retain their fluorescent label for long periods of time and withstand histological fixation and decalcification. In experimental rickets, no labeled serum protein is seen to be incorporated into the uncalcified rachitic osteoid. Its uptake begins, however, concomitantly with the onset of mineralization during the healing period. The results of experiments are interpreted in terms of a calcium-carrying serum protein being complexed and precipitated by osteoblast products to form an essential component of apposition zones which, possibly, initiates nucleation and the subsequent steps of calcification. Fractionation experiments to define the serum component(s) involved in this process, will be continued. So far, they have resulted in a fraction containing albumin, ₁-macroglobulin, transferrin, and haptoglobin.

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Zusammenfassung Gewisse Anteile von Fluorochrom-markiertem homologem Blutserum lassen sich nach parenteraler Verabreichung in der Knochensubstanz junger und erwachsener Ratten direkt nachweisen. Diese Serumproteine werden in hoher Konzentration während der Knochenbildung in die organische Matrix eingebaut. Sie behalten ihre Markierungsfluoreszenz für lange Zeit und widerstehen der Fixierung und der Entkalkung. Während experimenteller Rachitis ist eine Aufnahme dieser markierten Serumproteine in das unverkalkte rachitische Osteoid nicht festzustellen. Ihre Inkorporation beginnt jedoch wieder gleichzeitig mit dem Einsetzen der Verkalkung, wenn die Rachitis zur Ausheilung gebracht wird. Die experimentellen Resultate deuten darauf hin, daß ein calciumtragendes Serumprotein mit gewissen Produkten der Osteoblasten Komplexe bildet, dabei präzipitiert und zu einem Bestandteil der Appositionssäume wird, der möglicher Weise die Verkalkung der organischen Knochengrundsubstanz in Gang setzt. Fraktionierungsexperimente zur Bestimmung der an diesem Vorgang beteiligten Serumkomponente(n) sind noch nicht abgeschlossen. Sie halten derzeit bei einer Fraktion, die Albumin, -1-Makroglobuline, Transferrin und Haptoglobin enthält, und werden weiter fortgesetzt.

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Supported by United States Public Health Service Grant No. AM06705.