J. Bradley Aust

Radioactive iodinated human serum albumin as tracer agent for diagnosing and localizing intracranial lesions.

Various isotopes have been used to diagnose and localize intracranial lesions by the isotope- encephalometric technic described by Moore( 2 , 3 , 4 ). So far, diiodofluorescein has given the most satisfactory results and therefore gained the widest acceptance. However, at this clinic radioactive-iodinated-human-serum albumin has been used and appears to be as satisfactory, if not superior, to diiodofluores-cein. The iodination of human serum albumin (RIHSA‡) is carried out with ele-mental iodine in an essentially neutral buffer. One cc of RISHA contains 5 mg of human serum albumin with a salt concentration of approximately 2 mg( 6 ). Metabolic studies in both animals and humans have shown that RIHSA given intravenously remains in the blood stream for a long period of time. It is apparently gradually metabolised by the body and free iodine liberated. Although most of the radioactive iodine is excreted through the urine, about 5%percnt; of it is taken up by the thyroid gland by the end of 24 hours( 5 ). A small amount of RIHSA, which is not readily metabolized, diffuses out into the tissue and into lymphatics unchanged. About 1-2%percnt; of the tagged albumin can be obtained from the thoracic duct by the end of one hour. The liver, however, apparently does not participate in the excretion of RIHSA. It has been shown in experimental animals that only a neglibgible amount of RIHSA can be recovered in the bile( 5 ).

Tumor blood flow. II. Distribution of blood flow in experimental tumors.

From the Department of Surgery, University of Texas Medical School at San Antonio, Texas, and the Department of Surgery, University of Minnesota Medical School, Minneapolis, Minnesota. This work was supported in part by a research grant (T-156) from the American Cancer Society. The present blood-borne cancerocidal drugs and tumor antisera depend on contact of the agent with tumor cells. Therefore, knowledge of the circulation to solid cancer tissue is of fundamental interest.

Acquired Tolerance to Skin Homografts in Mice of Different Strains.

Summary Mice of the Ce, ZBC, and ZCe F1 stocks have been made tolerant to homologous skin transplantation of Z(C3H), Ce. C57 Bl and CBA strains by intravenous injection at birth of homologous spleen cells. However, the same procedure failed to induce tolerance in ZCe F1 mice when treated with homologous cells of either BALB/C or A strains.

Transfer of acquired tolerance to skin homografts in mice.

Summary Newborn mice of the ZBC strain injected intravenously with living spleen cells taken from donors of the same strain in which tolerance to Ce tissues was previously induced, became tolerant to this strain and accepted homologous skin grafts from Ce donors. This would indicate that acquired tolerance can be transferred to an isologous individual at birth by the intravenous injection of spleen cells taken from a tolerant donor.

Methods for reducing duration of parabiosis in development of tolerance to skin homografts in mice.

Summary Using C3H and (Ax C3H)F1 mice in parabiosis, this study was undertaken to find means of reducing the duration of parabiosis necessary for development of immunologic tolerance. Parabiosis in the usual way maintained for 8–10 days did not result in development of tolerance. When talc powder was sprinkled and mechanical abrasion employed, 25% of the grafted C3H mice became tolerant to the hybrid tissue. If talc powder was applied 6–7 days prior to parabiosis and the area of contact between parabiosis increased by creation of skin flaps, 85.7% of grafted C3H mice became tolerant to (Ax C3H)F1 skin.