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Transfer RNA and ribosomal RNA contain a number of methylated components in addition to the four major bases of their primary structure. (Dunn, 1959; Dunn et al., 1960: Dunn, 1961: Dunn et al., 1963: Hall, 1963) It has recently been demonstrated (Fleissner and Borek, 1962, 1963) and corroborated in many laboratories (Gold et al., 1963; Svensson et al., 1963; Starr, 1963) that the methylated bases of transfer RNA are acquired by transmethylation at the polynucleotide level of a preformed unmethylated polymer. The in vitro demonstration was facilitated -by the availability of methyl deficient transfer RNA which accumulates during methionine starvation of E. coli K12W6. However, the RNA formed in this relaxed mutant during methionine starvation also contains ribosomal RNA (Mandel and Borek, 1963) and hence should serve as an ideal substrate in a search for enzymes which methylate ribosomal RNA. In this communication we

Semen analysis was performed on 8 men, every 2 months, for a period of 8 months, after the application of the radiozinc spermatogensis test. Semen was examined for volume, cell count, motility, and abnormal forms. Results showed no evidence of any changes in semen parameters. Student's test was used to compare the data before the test with the data after the test, and no significant differences were seen. The radiozinc spermatogensis test seems safe, from a radiologic point of view, does not have an adverse effect on semen, and unlike testicular biopsy, saves the patient from surgical exposure. The radiozinc spermatogensis test can be applied as an important adjuvant measure in the diagnosis and prognosis of male infertility.

A total of 263 patients with histopathologically proved, well-differentiated papillary and follicular thyroid carcinoma were treated with sodium iodide I 131 after surgery. A 100% follow-up was achieved with a mean of 6.3 years, and an observation period of 0 to 20 years. The death rate in these patients was compared with the death rate in 50 patients with papillary and follicular carcinoma of the thyroid treated surgically before introduction of sodium iodide I 131 (control group), and followed for a mean of 6.7 years (0 to 20 years). These groups were matched in sex, but not in age distribution. In patients 40 years of age and older, the group treated with sodium iodide 1131 had a significantly lower death rate than the surgery-only group (P

INTRAVENOUS DOSES of I 131 -labelled sodium o -iodohippurate (Hippuran) or Hg 203 -labelled chlormerodrin (Neohydrin) are concentrated sufficiently by the kidneys to permit their anatomical visualization with the aid of a photoscanner. We have reported a preliminary evaluation of the use of the photoscanner in the diagnosis of renal disease. After an experience of more than 100 renal photoscans, we wish to document some of the more important clinical uses of this technique. Materials and Methods Scanning Equipment.—Scintiscans were performed using a 19-hole collimator, a 3" x 2" thallium activated sodium iodide crystal, a pulse height analyzer, and a pulsed light photorecording system. Technique—In the early part of the study scintiscans were performed with both I 131 sodium o-iodohippurate and Hg 203 chlormerodrin. Since February, 1961, all scintiscans have been performed with Hg 203 chlormerodrin. I 131 sodium o-iodohippurate scintiscans were performed during a slow intravenous infusion (2-4 μC. per minute) of 200 /μC. of I 131 sodium o-iodohippurate.

An evaluation was made of scintillation scanning in 18 patients suspected of having renal tumors. Neohydrin-Hg/sup 203/ was used in a single intravenous injection of 100 mu C. The method did not differentiate between tumors and cysts, and tumors which did not appreciably replace functioning renal tissue could not be detected. In spite of these limitations, it is of value when used in conjunction with routine excretory urography. (BBB)

Follow-up examinations were performed on 76% of 200 thyroid carcinoma patients treated at the University of Michigan Hospital over a 14-yr period. Twenty-two per cent of the patients died and 2% were lost to follow-up. In 82 patients, concentration of I 131 was demonstrable in metastases. In 52 of the 82, the metastases were to regional lymph nodes, and 35 of the 52 were apparently free of their thyroid carcinoma. In 30 of the 82, the metastases were to distant structures (lungs, bones), and 16 of the 30 showed complete clinical regression. Those patients who died of carcinoma did so within an average period of 2 yr after treatment, and no patient clinically free for 3 yr after completing treatment has had a recurrence to this date.

The incidence of hypothyroidism among 848 patients treated for hyperthyroidism with sodium iodide I 131 has been compared with the incidence among 121 patients treated for hyperthyroidism surgically. During follow-up periods ranging from less than a year to 16 years, at least 51% of those treated with sodium iodide I 131 and 28% of those surgically treated became hypothyroid. After the first year of follow-up study, the cumulative incidence of hypothyroidism increased 2.8% per year in the group treated with the radioactive compound and 1.7% in the group surgically treated. It is also estimated that within the first ten years after treatment, 70% of the group treated with sodium iodide I 131 and 43% of the group surgically treated will have become hypothyroid.

INERT CERAMIC MICROSPHERES containing beta emitting radioisotopes have been injected into the arterial supply of human cancers for irradiation treatment purposes. 1-3 Tissue counting radioautography revealed an even distribution pattern in the lungs when the microspheres were infused into the external jugular vein of the dog. Of the microspheres, 96 to 100% were found to be filtered out and retained in the arterioles of the lungs. We have used gamma emitting radioisotopes in these microspheres to visualize the lungs with a photoscanner. 4 Methods Ceramic microspheres 50±10 μ in diameter and containing Hg 203 with a radioactivity content of 5 μc of radioactivity per mg of labelled spheres were injected into the saphenous veins of mongrel dogs weighing about 12 kg (24.2 lb), during sodium pentothal anesthesia. Doses of microspheres weighing from 10 to 60 mg and assaying from 50 to 100 μc of radioactivity were administered in from 1