67Ga-binding substances in abscess and normal tissues

Mechanism of gallium 67 accumulation in inflammatory tissue

The present study was undertaken to elucidate the accumulation mechanism of gallium 67 in inflammatory tissue. 67Ga accumulation in inflammatory tissue was observed by macro- and microautoradiogram. Permeability indices were calculated for serum albumin from blood vessels into inflammatory and normal tissue. Neutrophils and macrophages did not play a major role in 67Ga accumulation in the inflammatory tissue because 67Ga could hardly be detected in the sites in which neutrophils were crowded; the accumulation was concentrated in the intercellular space around these cells in the tissue. Permeability indices for inflammatory tissue were much greater than those for normal tissues. It is thought from the present study and previously reported results that 67Ga, together with plasma from permeable blood vessels, readily penetrates the inflammatory tissue and stays there by binding to the acid mucopolysaccharide present in the tissue.

Relation between the location of elements in the periodic table and various organ-uptake rates

Fifty four elements and 65 radioactive compounds were examined to determine the organ uptake rates for rats 3, 24 and 48 h after i.v. injection of these compounds. They were prepared as carrier free nuclides, or containing a small amount of stable nuclide. Generally speaking, behaviors of K, Rb, Cs and Tl in all the organs were very similar to one another, but they differed from that of Na. Bivalent hard acids were avidly taken up into bone; therefore, uptake rates in soft tissues were very small. Hard acids of tri-, quadri- and pentavalence which were taken up into the soft tissue organs decreased more slowly from these organs than other ions. Soft acids such as Hg2+ were bound very firmly to the component in the kidney. Anions (with few exceptions), GeCl4 and SbCl3 were rapidly excreted in urine, so that the uptake rates in organs were low.

Distribution of 67Ga-citrate in abscess-induced rat by quantitative whole body autoradiography

Distribution of 67Ga-citrate in inflammatory tissues was determined, and correlation between the 67Ga-uptake and capillary permeability of plasma from blood vessels in the inflammatory tissue was elucidated, by quantitative whole body autoradiography and double tracer autoradiography. The distribution of 67Ga in inflammatory tissue was similar to that of 131I-HSA and 99mTc-HSA, which were applied as an index to the plasma element. These results showed that the capillary permeability of plasma from blood vessels in the inflammatory tissue increases, and this causes the 67Ga-uptake.

Distribution of 103Ru-chloride in tumor-bearing animals and the mechanism for accumulation in tumor and liver

Tumor uptake rates of 103Ru-chloride were smaller than those for 67Ga-citrate. In three tumors and liver, 103Ru in the mitochondrial fraction containing lysosome increased with time after the administration of 103Ru-chloride. The concentration of 103Ru was more dominant in connective tissue (especially inflammatory tissue) than in viable tumor tissue or in necrotic tissue. Quite large amounts of 103Ru in the tumor and liver were bound to the acid mucopolysaccharide whose molecular masses exceeded 40,000. Behavior of this nuclide was essentially similar to that of 67Ga.

A novel method for labelling of leukocytes with technetium-99m and its comparative evaluation for abscess scintigraphy

A new method, based on the pretreatment of leukocytes with glucoheptonate prior to treating with reduced 99mTc, has been developed for the preparation of 99mTc labelled leukocytes. The leukocytes labelled with a 99mTc concentration (5.59%/g tissue) similar to that of 111In-leukocytes (6.27%/g tissue), in the experimental abscess were in rat thigh. Concentration of 99mTc-leukocytes in blood at 24 h was only about 35% as compared to that of 111In-leukocytes. Biodistribution in the rat organs was similar in both cases, except in the liver where 99mTc-leukocytes exhibited about 4-fold greater concentration. Images of experimental abscess in rat by using 99mTc-leukocytes were comparable to those obtained with 111In-leukocytes.

67Ga accumulation in inflammatory lesion and its mechanism: comparison with malignant tumor

The accumulation of 67Ga in inflammatory lesions increased with time after injection of turpentine oil and reached a plateau 5 days later. At that time the uptake in the lesions was larger than any other tissue, after ten days the lesion uptake decreased. In experiments using rats which had been kept for 5 days after subcutaneous injection of turpentine oil, the accumulation of 67Ga in inflammatory lesions increased with time until six days after administration of 67Ga-citrate. It is clear from this study that 67Ga is avidly accumulated in areas where the subcutaneous tissue is infiltrated with neutrophils and macrophages, that it is not accumulated at the sites in which neutrophils are crowded, that nuclear material, mitochondria, lysosomes and microsomes do not play a major role in 67Ga accumulation in the lesion and that the main binding acid mucopolysaccharide in the lesion is a acid mucopolysaccharide which is none of the following: keratan sulfate, heparan sulfate, heparin, or chondroitin sulfate A, B or C. It is presumed that the main 67Ga binding acid mucopolysaccharide is keratan polysulfate (or other oversulfated acid mucopolysaccharides).

67Ga-binding substances in stomach, small intestine, pancreas, and muscle

Normal male rats were injected with either gallium citrate Ga 67 or sodium sulfate S 35. After 24 h, the stomach, small intestine, pancreas, and muscle were excised and homogenized. After the removal of the nuclear fraction, each of these homogenates was digested with protease. After digestion, the supernatants of the reaction mixtures were applied to a Sephadex-G-100 column. The radioactivity was eluted with buffer solution. The resultant eluates were analyzed for radioactivity and the levels of proteins, uronic acids, and sialic acids. In all four organs, sizable amounts of 67Ga were bound to sulfated acid mucopolysaccharides with molecular masses of about 10,000 daltons and to sulfated acid mucopolysaccharides, a species whose molecular masses exceed 40,000 daltons. In the stomach, large amounts of 67Ga were bound to sulfated acid mucopolysaccharides with molecular masses of about 10,000 daltons. From these results, it is obvious that the main 67Ga-binding substances in these four organs are sulfated acid mucopolysaccharides, and that these acid mucopolysaccharides play the most important role in the concentration of 67Ga in these organs.

Species of 67Ga-binding acid mucopolysaccharide in liver

It was determined from measuring neutral saccharide in the structure that the principal 67Ga-binding acid mucopolysaccharide in liver was keratan sulfate and/or keratan polysulfate. On the other hand, it was clarified from the results of mucopolysaccharase treatment that the main 67Ga-binding acid mucopolysaccharide in liver was not either one of keratan sulfate, heparan sulfate, heparin, chondroitin sulfate A, B and C. Based on the present results, it was deduced that the main 67Ga-binding acid mucopolysaccharide in liver was keratan polysulfate.