Lymphocyte labeling with technetium-99m-HMPAO: a radiotoxicity study using the micronucleus assay.

The cytogenetic radiation damage to lymphocytes after in-vitro labeling of mixed leukocytes and isolated lymphocytes with 99mTc-hexamethylpropyleneamine oxime (HMPAO) was evaluated using the cytokinesis-blocked micronucleus assay. A direct assessment of the radiation damage to the lymphocytes after a labeling procedure of leukocytes separated from 46 ml blood with 740 MBq of 99mTc-HMPAO was not possible due to an almost complete impairment of the proliferative capacity. By starting with isolated lymphocytes, the number of micronuclei was studied versus the intracellular activity concentration in the range 0-3 MBq/10(7) lymphocytes for three donors. A comparison of these results with the dose response of the micronucleus incidence in lymphocytes after in-vitro irradiation with x-rays allowed an individual assessment of the x-ray dose, inducing the equivalent amount of clastogenic damage as the intracellular activity after 99mTc-HMPAO labeling. Based on an extrapolation of these data, the radiation damage of the lymphocytes due to self-irradiation in a labeling procedure of leukocytes with 740 MBq of 99mTc-HMPAO was estimated to be equivalent to 26 Gy of x-rays. Due to the observed almost complete inhibition of the proliferative capacity at this high dose level, the increased risk for a lymphoid malignancy after administration of isolated lymphocytes or mixed leukocytes labeled with 99mTc-HMPAO activities sufficient for scintigraphy can be regarded as small.

Analogy between tumor uptake of technetium(V)-99m dimercaptosuccinic acid (DMSA) and technetium-99m-MDP.

Sixty patients with a variety of malignant tumors were examined with Tc-99m(V) dimercaptosuccinic acid (DMSA) prepared by modification of a commercially available DMSA kit. Significant uptake of Tc-99m(V)-DMSA was observed in a number of tumors, offering additional clinically useful information. In the majority of cases in this study, however, the benefit of the Tc-99m(V)-DMSA image was limited because of low sensitivity. The most striking observation was the similarity between the tumor concentration of Tc-99m(V)-DMSA and the Tc-99m-MDP uptake in the tumor on the regular bone image. Therefore, patients with Tc-99m-MDP uptake in nonosseous tumor sites on the bone scan may be suitable candidates for tumor imaging with Tc-99m(V)-DMSA.

Influence of continuous ambulatory peritoneal dialysis on the anemia of endstage renal disease.

To evaluate the effect of continuous ambulatory peritoneal dialysis (CAPD) on the anemia of endstage renal disease, serial measurements of red cell mass and other hematological parameters were performed in 34 patients. Twenty-five patients were measured at the start and at 6 months (group 1), 13 at the start, at 6 and 12 months (group 2), and 11 were followed during their second year of treatment with measurements at 12, 18, and 24 months (group 3). In group 1 the hematocrit rose from 24.6 +/- 0.9 to 29.9 +/- 0.8% (P less than 0.01). The red cell mass increased from 879 +/- 44 to 1019 +/- 47 ml (P less than 0.01). The calculated plasma volume decreased from 2915 +/- 174 to 2568 +/- 136 ml (P less than 0.01). In group 2 at 6 months the hematocrit rose from 24.7 +/- 1.2 to 30.7 +/- 1.0% (P less than 0.01); the red cell mass increased from 924 +/- 66 to 1059 +/- 71 ml (P less than 0.05). The calculated plasma volume decreased at 6 months from 3001 +/- 201 to 2555 +/- 170 ml (P less than 0.01). No significant changes occurred between 6 and 12 months. In group 3 no significant changes in hematocrit, red cell mass, or plasma volume were observed. It is concluded that the rise in hematocrit in CAPD patients is due to an increase in red cell mass and also to a decrease in plasma volume. These changes are manifest within 6 months of treatment. The rise in red cell mass represents an improvement in renal anemia in these patients.

Total body irradiation with 8 MeV X-rays in generalized malignant disease.

The authors describe their experience with total body irradiation (TBI) with 8 MeV-x rays in the treatment of disseminated tumors. With a dose of 125 rad, given three times with 2-week intervals, some objective remissions (6/26) were obtained, especially in patients with lymphomas. For solid tumors only subjective improvement could be achieved. The side-effects were acceptable. The authors came to the conclusion that total body irradiation may be an alternative to chemotherapy for certain cases of generalized cancer.