Merle K. Loken

Radionuclide bolus angiography: A technique for verification of brain death in infants and children

Fifteen infants and children, 11 of whom had clinical brain death and four of whom were comatose, were evaluated with the radionuclide bolus study and electroencephalography. Clinical criteria for brain death included: (1) absence of spontaneous respirations, (2) absence of cephalic reflexes, and (3) unresponsiveness. Results demonstrated complete correlation among clinical examination, EEG, and radionuclide study in 79% of cases. An approach to the evaluation of the infant or child with possible brain death is outlined utilizing serial examinations, radionuclide bolus study, and electroencephalography. The radionuclide bolus study appears to be a safe, rapid, portable technique which can be used for this purpose in infants and children.

A NEW TECHNIQUE FOR HIGH‐RESOLUTION DENSITY GRADIENT‐SEPARATION OF BONE‐MARROW CELLS*

A new technique with minimal artifacts was developed for high-resolution density-gradient separation of viable cells. Differences as small as 0.002 in the density of the cells can be easily detected. It has been possible to detect differences of 0.0005 with careful manipulation. The development of this technique has necessitated the construction of a new centrifuge head, the preparation of a new suspension medium, and a new density gradient, and finally the development of a new centrifuge tube. Results on experiments on the bone marrow of three dogs are reported.

RADIATION HORMESIS : ITS EMERGING SIGNIFICANCE IN MEDICAL PRACTICE

Because of the strong scientific evidence in support of radiation hormesis, we can no longer ignore this concept. There is, however, need for additional, carefully documented investigations in selected biological systems exposed to LLIR if the matter of radiation hormesis is to be settled once and for all. This need should be addressed without delay, as the matter of benefits derived from LLIR exposure could have major economic and epidemiologic implications. If radiation hormesis becomes firmly established, the requirements for LLIR protection might be relaxed, leading to a sizable cost saving, and the fear of nuclear energy should abate. If this happens, the evergrowing problems associated with energy production from fossil fuels on the one hand and the continued improvements in nuclear reactor technology on the other, will force a world-wide reassessment of risks and benefits associated with nuclear energy. Furthermore, as discussed herein, the major source of exposure from background radiation comes from the inhalation of radon gas. The very high cost associated with effective radon abatement would lead to an abandonment of this mitigation effort so that the limited funds available to improve public health world wide could be used more effectively elsewhere. Thus, we conclude that the time is now to consider eliminating the concept of the radiation paradigm from scientific thinking. We must not continue to unequivocally accept the propositions that 1) all radiation is harmful and 2) that the health effects of LLIR may be directly inferred by scaling down from known deleterious high-dose effects, in as much as there is no scientific basis for an agent not to cause multiple effects.(ABSTRACT TRUNCATED AT 250 WORDS)

Grading of reflux by radionuclide cystography

Over a three-year period, radionuclide cystography (RC) was performed on 145 patients. Of these, 31 nephroureteral units in 25 patients demonstrated vesicoureteral reflux by RC and also by radiographic cystography (XC). The RC and XC studies were performed within three months of one another. The grading of reflux was determined by RC and then compared with that of XC using the criteria for grading as established by the International Reflux Study Committee (IRSC). Of 18 nephroureteral units in 14 patients with grade II reflux by XC, 14 were similarly graded by RC (78%). Of five nephroureteral units in five patients with grade III reflux by XC, the correlation by RC was 100%. However, when grades II and III were combined into a single category of low-grade reflux, the correlation achieved between the two cystographic techniques was 100%. Of five nephroureteral units in four patients with grade IV reflux by XC, the correlation was 60%, and in three units in two patients with grade V reflux the correlation was 100%. When grades IV and V are combined into a category of high-grade reflux, a correlation of 100% is achieved. When the reflux is graded into the five IRSC categories, the overall unequivocal correlation between the two studies is 80%. However, when only two categories are used (low grade = grades II and III, and high grade = grades IV and V), a correlation of 100% is obtained.

Comparison of the distribution and binding of monoclonal antibodies labeled with 131-iodine or 111-indium

The distribution of two monoclonal antibodies with reactivity against human leukemia/lymphoma associated antigens (BA-1 antibody) and carcinoembryonic antigen (202 antibody) when labeled with 131I or 111In was studied in normal Balb/c mice. The BA-1 antibody of the IgM subclass was labeled with 131I by the micro iodine monochloride method at a 12:1 molar ratio and with 111In by the cyclic DTPA anhydride method at a 10:1 molar ratio. In vitro, the 131I-labeled BA-1 antibody bound 35.5% to 107 KM-3 leukemic cells while the 111In-labeled BA-1 antibody bound 29.9% to the same number of KM-3 cells. In vivo, the 111In-labeled BA-1 antibody showed a higher accumulation in liver, spleen, and kidney than the 131I-labeled BA-1 antibody. The 202 antibody of the IgG1 subclass was labeled with 131I at a 5:1 molar ratio and with 111In at a 7:1 molar ratio. In vitro, the 131I-labeled 202 antibody bound 30.9%, 27.4%, and 30.0% to 107 CO-112, WIDR, and LS-174T colon cancer cells, respectively. The 111In-labeled 202 antibody bound 20.5%, 30.2%, and 33.6%, respectively to the same number of colon cancer cells. In vivo, the 131I-labeled 202 antibody showed a higher tissue to blood ratio in liver, spleen, and kidney than the 111In-labeled 202 antibody. The data indicate that the relative distribution of 131I-labeled versus 111In-labeled monoclonal antibody may depend on the immunoglobulin subclass of the antibody and the molar ratio used in labeling.

In-111-labeled leukocytes in the diagnosis of rejection and cytomegalovirus infection in renal transplant patients

lndium-111-labeled (ln-111) leukocytes have been shown to be useful in the localization of inflammatory processes, including renal transplant rejection. Using previously reported labeling methods, 63 studies with this agent have been performed in 53 renal transplant patients. Indications for study included suspected rejection or cytomegalovirus (CMV) infection. Studies were performed in 33 men and 20 women, with ages ranging from 6 to 68 years. Autologous cells were normally used for labeling, although leukocytes obtained from ABO-compatible donors were used in three subjects. Rectilinear scanner and/or scintillation camera images were obtained at 24 hours after intravenous administration of 0.1 to 0.6 mCi of ln-111-leukocytes. There was abnormal uptake of ln-111-leukocytes in the transplanted kidney in 11 of 15 cases of rejection. In three additional cases of increased transplant uptake, CMV infection was present in two. Abnormal lung uptake was present in 13 of 14 patients with CMV infection. In four additional cases, increased lung uptake was associated with other pulmonary inflammatory disease. Increased lung activity was not seen in patients with uncomplicated transplant rejection. These results suggest that ln-111-leukocyte imaging may be useful in the differential diagnosis of rejection versus CMV infection in renal transplant patients.

Arteriovenous Complications Associated with Renal Transplantation

Angiography and 131I-Hippuran renography were performed in 9 cases of early postoperative kidney transplant dysfunction. The renograms were abnormal in each case but were diagnostic in only the 2 cases of arterial thrombosis. Arteriography and venography demonstrated the cause of transplant failure in the other 7 cases as arterial stenosis, renal vein thrombosis, or massive pelvic hematoma. Prompt recognition and correction of these complications led to prolonged survival of the renal transplants in 4 of the 9 patients.

Regional Pulmonary Function Evaluation Using Xenon 133, a Scintillation Camera, and Computer'

FOR THE PAST three years, xenon 133 and a scintillation (Anger) camera have been used extensively in our Nuclear Medicine Clinic to evaluate pulmonary function and measure regional blood flow (1–3). This report is a follow-up of these studies in selected patients with pulmonary disease, including our experience with the use of a computer2 for data processing. Materials and Methods One-curie ampules of 133Xe are received at weekly intervals from Oak Ridge National Laboratories. The gas is transferred into sterile saline solution in concentrations up to 5 mCi Xe/ml. Details of the technic involved have been discussed elsewhere (1,2). Our scintillation camera is equipped with bi-alkali cathode photomultiplier tubes which have a relatively low work function for electron release; for this reason, acceptable statistical information concerning the positioning of individual scintillations is obtainable despite the relatively low energy of the gamma rays emitted by 133Xe (81 keY). These cathode tubes, together wit...

Regional Ventilation in the Differential Diagnosis of Pulmonary Embolism

In the diagnosis of pulmonary embolism by lung scanning, clinical errors of interpretation may arise. Diseases that affect the distribution of pulmonary blood flow, such as pulmonary emphysema and bronchial asthma, may be confused with pulmonary embolism.With the addition of ventilation studies with 133xenon to the perfusion scans, distinct differences appear between patients with emboli and those with obstructive lung disease. In patients with pulmonary emboli, ventilation is preserved in the areas of decreased perfusion, whereas patients with obstructive lung disease show both decreased ventilation and perfusion in the affected areas.

Clinical use of indium-111 labeled blood products.

Following the introduction of In-111 oxine as a label for blood cells by McAffee and Thakur in 1976, these procedures have become increasingly important in the practice of nuclear medicine. Of particular interest are studies involving the use of labeled leukocytes for the detection of focal infection. The clinical utility of labeled platelets is less well developed, although the use of platelets to detect the formation of thrombi in blood vessels and on vascular grafts and prostheses is gaining prominence. This report summarizes the techniques presently employed at the University of Minnesota for the labeling of blood products, and their clinical use. Consideration also is given to the desired expertise and cost factors involved in the labeling of leukocytes and platelets.