The experimental production of Renaut bodies.

Renaut bodies are loosely-textured whorled, cell-sparse structures found in the subperineurial space of peripheral nerves. Although described in 1881, their significance is still debated. Rats were placed in wire-mesh cages for 4 days to 6 weeks and the lateral and medial plantar nerves were sequentially removed. The initial change was the presence of endoneurial edema which dissected and displaced nerve fibers producing an endoneurial cleft. With the influx of fibroblasts, these clefts became discretely separated by circumferentially oriented processes. Over time the clefts enlarged and became filled with loosely-textured amorphous and fibrillar material as well as collagen. The Renaut bodies ranged from 15 to 80 microns in diameter. In this model the Renaut bodies formed at the maximum site of compression of the lateral plantar nerve. The fibroblasts appeared to be derived from the endoneurial connective tissue and were not the result of degenerating endoneurial structures. Renaut body formation was independent of axonal degeneration. The present study strongly suggests that Renaut bodies are a response to repeated mechanical stress.

Radiobiological effects of 131I and 125I on the DNA of the rat thyroid. I. Comparative study with emphasis on the postradiation hypothyroidism occurrence.

One of the major disadvantages of the use of 131I in the treatment of thyrotoxicosis is the development of hypothyroidism. Alternatively, 125I has been proposed for thyrotoxicosis therapy, and was thought to be preferable to 131I because of the short range of its emitted soft electrons. Several studies have shown 125I to be as effective as 131I in the treatment of thyrotoxicosis, and equally likely to produce hypothyroidism. This work compared the radiobiological effects of 131I and 125I given in doses to deliver the same amount of radiation to the rat thyroid gland. These effects were studied by in vivo determination of single-strand DNA breaks by alkaline sucrose gradient sedimentation using the DABA fluorescent technique to detect the DNA. Serum T4 and TSH concentrations and percentage T3 uptake were determined by RIA. The incidence of hypothyroidism following 131I and 125I therapy was found to be the same (10% in each group). The extent of DNA damage following 125I therapy was greater than the damage induced by a larger dose of 131I.