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The diffusion function of 25 MV Roentgen rays in a tissue-equivalent material was determined experimentally as a function of the size of the beam and of the depth into the material. In order to characterize the beam, the attenuation of the beam in various materials was previously investigated. The results of the investigation demonstrate the important contribution of diffused radiation to the dose when using very high energy radiation.

1 The aldol breakdown of l-threonine and l-allothreonine in rat liver is catalyzed by systems localized in the soluble fraction of the homogenate. 2 Evidence in presented that two different enzymes, indicated as “threonine aldolase” and “allothreonine aldolase”, are involved in the breakdown of the two amino acids

The diffusion function of 25 MV Roentgen rays in a tissue-equivalent material was determined experimentally as a function of the size of the beam and of the depth into the material. In order to characterize the beam, the attenuation of the beam in various materials was previously investigated. The results of the investigation demonstrate the important contribution of diffused radiation to the dose when using very high energy radiation.

The study of the possibilities of new DNA synthesis by the Sternberg-Reed cells of Hodgkin disease was done with tritated thymidine and autoradiography. The results showed that after incubation pulses of 30 and 60 minutes cells with lobulated nucleus, binucleated and trinucleated cells, identifiable to the diagnostic Sternberg-Reed cells, had possibilities of new DNA synthesis. This points to a more dynamic interpretation of this cell that was considered without chances of cnromosome replication.

The aim of the work was the evaluation of the dose delivered to the axilla during endocurietherapy for carcinoma of the breast using Iridium 192. The position of the radioactive material with respect to the axillary zone differing with the patient seated or lying, the authors carried out an vivo dosimetric study using Lithium fluoride. They refer to the chief properties of Lithium fluoride which render it the dosimetric agent of choice for clinical work and give details of their experimental conditions, stressing the problems encountered in practice (response in relation to dose, mass of thermoluminescent powder to use, fading, regeneration etc.). They then describe the technique used for placing the thermoluminescent dosimeter in the axillary zone adjacent to the target volume irradiated. Results concerning 43 patients made possible the establishment of a significant correlation between the dose delivered to the axillary region and the site of implantation of the radioactive material in the breast, and show that, with identical tumour doses, this dose is little dependent upon the structure of the radioactive implant itself. They conclude that the dose delivered to the axillary region is of the order of 25% of the tumour dose if the radioactive implant is localised in the axillary tail, 10% if it is in the upper outer quadrant and negligeable if it is elsewhere.

The behavior of xanthine oxidase in the jejunal mucosa of patients with gout and in the liver of normal subjects during secondary drug-induced hyperuricemia was studied. Xanthine oxidase activity was not increased significantly in the jejunal mucosa of patients with gout, whereas an RNA, hypoxanthine, EA-TDA, or fructose load in normal subjects caused liver xanthine oxidase levels to rise to values that were two- to fourfold higher than those for the control group. The results indicated that previously reported increases in liver xanthine oxidase levels in patients with gout, who were overexcretors, were neither primary nor genetically determined but were related to increased production of the enzyme.

Benzodiarone has a strong uricosuric effect, which is probably due not only to an inhibitory effect on renal tubular uric acid reabsorption. Experiments have been carried out in vitro which demonstrate that the drug exhibits a non-competitive inhibition on rat liver xanthine oxidase. The role that this effect may play in vivo is discussed.

Artículo sobre Alicia Alonso.