Ruth L. Goodland

High Specific Activity Labeling of Protein with I131 by the Iodine Monochloride Method.

Summary A modified iodine monochloride method suitable for preparing I131-labeled proteins of a high degree of radioactivity is described, and results are given. Hydrogen peroxide present in high level I131 preparations is destroyed with catalase. Then IC1 is added to a mixture of the I131 as iodide and the protein to be iodinated. Total iodine content of I131 preparations sets a limit on the specific activity of I131-labeled proteins that can be achieved with a low degree of iodination. In the two commonly used methods for producing I131 (fission of U235 and thermal neutron irradiation of natural tellurium) stable I127 and long-lived I129 are also formed. Analysis showed the total iodine content of fission product I131, as received from Oak Ridge National Laboratory soon after processing, to average 2.4 μg per 100 mc, 3 times the amount present as I131 (0.8 μg/100 mc). For I131 produced from tellurium it was substantially greater. Since the ratio of total iodine to I131 increases with time after processing, freshly produced I131 is necessary to make very high level labeled preparations. Precautions to prevent protein damage as a result of high level labeling procedures are described.

In vivo and in vitro studies of labeled antibodies against rat kidney and Walker carcinoma.

Summary An in vitro method is described for demonstrating the binding by rat organ homogenates of I131 labeled antibodies produced by rabbits immunized with particular rat organs. By this test anti-kidney antibodies show specificity for kidney compared with other rat tissues, and anti-Walker rat carcinoma 256 antibodies specificity for this tumor tissue. These data are compared with I131 distributions found after injection of these antibodies by various routes into living rats. The results suggest that nearly all of these antibody molecules are also general anti-rat antibodies in that they are bound by components of other rat tissues. Such factors as relative circulation rates, blood vessel permeability to proteins, and intracellular or extracellular location of antigens, as well as relative organ specificity of antibodies as demonstrated by in vitro experiments, are probably therefore important in determining the localization of such antibodies in animal injection experiments.

Detection of Preformed Venous Thrombi in Dogs by Means of I 131 -Labeled Antibodies to Dog Fibrinogen

Dogs with thrombin-induced thrombi received I131 rabbit antibody to dog fibrinogen and a day later were given antiserum to the rabbit gamma globulin. Scintillation scanning techniques successfully detected the site of thrombosis. Excision of the thrombi and surrounding blood vessels demonstrated deposition of radioactivity in the lesion. The immunologic removal of the gamma globulin from the circulating blood increased the difference between the radioactivity deposited in the lesion and that present in the blood. This accentuates the lesion and offers potential diagnostic advantage.

Localization of I131 Labeled Antibody to Rat Fibrin in Transplantable Rat Lymphosarcoma.

Summary Rabbits were immunized with rat fibrin and the resulting antisera clotted with normal rat plasma. From the clot a substance was isolated and labeled with I131 that showed a strong tendency to bind to rat fibrin clots formed in its presence. This substance, presumably an antibody to rat fibrin, when injected intravenously into rats bearing the transplantable Murphy-Sturm lymphosarcoma localized with a high degree of preferentiality in this tumor.

SERUM VITAMIN E LEVELS IN COMPLICATIONS OF PREGNANCY

Since the development of an accurate method for the estimation of total tocopherol in serum by Quaife et u Z . , ~ . the direct biochemical investigation of the relation of tocopherol to complications of pregnancy has been practical. If sufficient differences exist between the vitamin E metabolism or supply in normal and abnormal pregnancy to be of etiological significance, it seemed possible that these differences would be reflected in the vitamin E blood levels. In this study, the serum tocopherol levels in abortion, prematurity, pre-eclampsia, and essential hypertension complicating pregnancy have been compared with those of normal pregnant women at corresponding stages of gestation, Observations on the increase of vitamin E in the blood of pregnant women as gestation progresses are already a~ai lable .~, 6 . G Several European workers have also reported on the tocopherol content of the serum in women with spontaneous abortions, but the results are not consistent. Three of these7, * * fail to find any significant difference, while onelo reports significantly lower tocopherol values in abortion. In the paper by Rauramo in this monograph,lI vitamin E values for “toxemia” are given which suggest that patients with this condition have lower blood serum leveIs. It is evident that these results are in part contradictory. Furthermore, the results reported by Kauramo” and several of the above are in a range of serum tocopherol encountered only rarely in Rochester, New York, patients. Also pertinent to the present study are the reports that there is no detectable variation in vitamin E blood levels before and after menstruation or a t different stages in the menstrual cycle.6, l2 D’01iveyra13 does not find a lower vitamin E in pre-eclampsia and concludes that Shute’s’l theory of the relation between pre-eclampsia and tocopherol is incorrect.

Use of urea and salicylate to elute antibody from insoluble antigen.

Summary Solutions of 16–32% urea and of 10% sodium salicylate were used to separate I131 labeled rabbit anti-rat organ antibodies from insoluble rat organ residues acting as antigens. Following removal of these eluting agents, the antibody retained its specificity for rat organs as measured by in vivo and in vitro technics. Measured by in vivo technics, rabbit gamma globulin was resistant to the altering or denaturing effect of these reagents.