Studies on the sites expressing evolutionary changes in the structure of eukaryotic 5S ribosomal RNA

We have determined the complete sequences of 5S rRNAs from a lamprey (Lampetra reissneri), a lancelet (Branchiostoma belcheri), silkworms (Philosamia cynthia ricini, Bombyx mori, Antheraea pernyi), and a silkworm hybrid (artificially fertilized hybrid species of Philosamia cynthia ricini male x Bombyx mori female), as well as those of cotton seeds (Gossypium hirsutum L.). Having compared more than 170 eukaryotic 5S rRNAs of which seven sequences have been determined by our group as mentioned above, we have found that the "evolutionary sites" that exist at special locations in these structures are closely related to the evolution of eukaryotes. The changes proceed step by step in an orderly way, i.e., the change in nucleotide residues of the "evolutionary sites" depends on the order of the evolution of the species and shows group-specific patterns.

The superiority of combined therapy (surgery and postoperative irradiation) in parotid cancer

A retrospective evaluation was done on 120 patients treated for parotid cancer. The aim of the study was to establish the role of postoperative radiation therapy. Fifty-nine patients were treated by surgery plus postoperative radiation therapy. Two patients were treated by preoperative irradiation. The overall 5-, 10-, and 15-year survival rates were 81%, 62%, and 65%, respectively. Postoperative radiation therapy proved to increase local control over surgery alone whenever (1) there was locally advanced disease, (2) the tumor belonged to a so-called poorly differentiated variety, (3) the treatment was given for a recurrent lesion, and/or (4) there was tumor involvement of the facial nerve. It did not appear that postoperative radiation therapy increased the survival for patients with low-grade malignant tumors. Radiation therapy should be given as early as possible after surgery and the optimum dose ranges from 3,000 to 5,000 rad given in three to five weeks, respectively.