. Adventures in radioisotope research;. Radioactive tracers; Radiobiology. 982 ADVENTURES IN RADIOISOTOPE RESEARCH making use of radio-phosphorus/**) Here we refer to the first turnover studies of body constituents with the help of a radioactive tracer, which were carried out simultaneously with the above-mentioned first investi- gations by ScHOENHEiMER and Rittenberg, who used deuterium as an indicator. Blood-plasma phosphate was found to interchange very rapidly with the uppermost phosphate layer of the apatite-like crystallites. This rapid interchange is followed by a slower one due to a sl
. Adventures in radioisotope research;. Radioactive tracers; Radiobiology. 982 ADVENTURES IN RADIOISOTOPE RESEARCH making use of radio-phosphorus/**) Here we refer to the first turnover studies of body constituents with the help of a radioactive tracer, which were carried out simultaneously with the above-mentioned first investi- gations by ScHOENHEiMER and Rittenberg, who used deuterium as an indicator. Blood-plasma phosphate was found to interchange very rapidly with the uppermost phosphate layer of the apatite-like crystallites. This rapid interchange is followed by a slower one due to a slow recrystallization Epiphysis. days Fjci, 4. _ Extent of replacement of rabbit's bone phosphorus by labelled phosphorus (reproduced, with permission, from Biochem. J. 34, 532 (1940) of the apatite crystals. Some molecular layers go into solution while others are formed with the participation of labelled phosphate. Such layers will be comparatively strongly active in the early phase of the experiment. Owing to the decrease in the ^^p content of the plasma and lymph with time, they will be much less active in later phases. On top of a strongly active layer, slightly active layers may be deposit- ed, protecting the first layer from dissolution. The great complexity of 32P distribution in the skeleton apatite frustrates, or at least makes extremely difficult, a quantitative determination of the extent of renewal of the mineral constituents of the bone when labelled phosphate is admi- nistered only at the start of the experiment. We arrive at such a result when administering daily repetitions of labelled phosphate, thus keeping the level of plasma activity constant. By applying this technique, which is much less convenient, and by comparing the specific activities of the bone inorganic P and plasma inorganic P at the end of the experiment, we obtain a figure indicating the percentage of the renewed skeleton. Results obtained with rabbits, seen in Fig. 4, show that after the lapse ^
Size: 2067px × 1209px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookcollectionbiodiversity, bookleafnumber478
