The effect of FeCl3 on the accumulation of gallium-67 into inflammatory and normal tissues

The Effect of Blood Decrease on 67Ga Uptake by the Liver in Partially Hepatectomized Rats

As (67)Ga is injected into the blood, (67)Ga is immediately bound to transferrin (Tf) and transported to various tissues and the Tf-(67)Ga complex binds to Tf receptor on various tissues. In partial hepatectomy (PH) a part of blood in circulation is lost together with removed liver tissues, consequently the amounts of blood cells and Tf in circulation decrease. In order to investigate the effect of those decreases on (67)Ga uptake by the liver, we compared the uptake in partially hepatectomized rats with that in venesectioned rats in which only a part of blood in circulation decreased. A two-thirds PH was performed. Two milliliters of blood was venesectioned. Each treated rat was intraveneously injected with (67)Ga. The changes of erythrocyte and reticulocyte contents after PH did not differ from those after venesection (VS) at all. But (67)Ga uptake by reticulocytes significantly increased after VS but did not after PH. On the other hand, (67)Ga uptake by the liver significantly increased after PH but did not after VS. These differences must be related to the different expression of Tf receptors on the liver after PH and VS.

Gallium in cancer treatment

Gallium (Ga) is the second metal ion, after platinum, to be used in cancer treatment. Its activities are numerous and various. It modifies three-dimensional structure of DNA and inhibits its synthesis, modulates protein synthesis, inhibits the activity of a number of enzymes, such as ATPases, DNA polymerases, ribonucleotide reductase and tyrosine-specific protein phosphatase. Ga alters plasma membrane permeability and mitochondrial functions. Ga salts are taken up more efficiently and more specifically by tumour cells when orally administered. New compounds have been prepared: Ga maltolate, doxorubicin-Ga-transferrin conjugate and Tris(8-quinolinolato)Ga(III), which show interesting activities. Ga toxicity is well documented in vitro and in vivo in animals. In humans, the oral administration Ga is less toxic, and allows a chronic treatment, allowing an improvement of its bioavailability in tumours, by comparison with the parenteral use. The anticancer activity of Ga salts has been demonstrated but other effects have also been noted such as many bone effects that could be useful in bone metastatic patients. Its has also been shown that a long period of administration could induce tumour fibrosis. Ga is synergistic with other anticancer drugs. Although not as potent as platinum in vitro, the anticancer activity of Ga should not be ignored, but the schedule of administration still needs to be optimised and new compounds are now under clinical investigations.

The role of gallium-67 imaging in the detection of foci in recent cases of fever of unknown origin

We have assembled data from patients with fever of unknown origin who underwent gallium scintigraphy during the past 5 years in order to obtain a more current sampling of patients, and evaluated the role of gallium scintigraphy retrospectively. Of the 36 patients studied, gallium scintigraphy was positive and contributed to the detection of the foci or fever origins in 17 (47.2%). The ratio of neoplastic diseases with myeloproliferative and with lymphoproliferative disorders was relatively high compared with previous reports. However, gallium scintigraphy did not contribute to the diagnosis of collagen disease. With the ability to detect both inflammatory and neoplastic lesions, gallium scintigraphy was useful in detecting the foci of fevers of unknown origin.

67Ga in transferrin-unbound form is taken up by inflamed liver of mouse treated with CCl4

In order to investigate whether or not transferrin is involved in the uptake of 67Ga by inflamed liver (acute inflammatory tissues) the uptake of 67Ga by the liver of mice treated with carbon tetrachloride (CCl4) was studied. The serum GPT value reached its maximum on the 1st day after the CCl4 treatment. The uptake of 67Ga by the liver also reached its maximum on the 1st day after the CCl4 treatment and the amount uptaken into inflamed liver was about 6 times that uptaken into normal liver. On the other hand, the uptake of 125I-transferrin into inflamed liver on the 1st day after CCl4 treatment was only about 1.6 times that into normal liver. Moreover, cold Fe3+ decreased the uptake of 67Ga by normal liver but increased the uptake of 67Ga by inflamed liver. These results show that transferrin plays an important role in the uptake of 67Ga by normal liver but not by inflamed liver, i.e. 67Ga in the transferrin-unbound form is preferentially taken up by inflamed liver.

111In (III) uptake by inflammatory and normal tissues

Tissue distributions of 111In (III) in the rats bearing granuloma, inflammatory tissue induced by turpentine oil, were compared with those of 67Ga. The results showed that indium-111 resembles 67Ga in the manner of uptake by inflammatory and normal soft tissues. The effect of cold-InCl3 on 111In (III) uptake showed that transferrin is not involved in the uptake of 111In (III) into inflammatory tissues but is involved in the uptake into liver and spleen.