Study on suppressed uptake by the liver in 67Ga scintigraphy

During the past 3 years, we have performed 1525 studies of 67Ga scintigraphy and 38 cases of these showed suppressed liver uptake; 19 cases after chemotherapy, 13 cases with liver dysfunction and 6 cases with competitive blockade. Many cases in chemotherapy used cyclophosphamide and vincristine, and were performed 67Ga scan within 1 week after chemotherapy. In cases showed suppressed uptake by liver after chemotherapy, serum Fe was markedly increased and UIBC was markedly decreased (p less than 0.01). This suggested that serum Fe influenced suppressed uptake by liver more than carrier-protein, disturbed hepatic cells, and receptors.     

Preparation and biodistribution of [67Ga]-DTPA-gonadorelin in normal rats

Gonadorelin was successively labeled with [⁶⁷Ga]-gallium chloride after residulation with freshly prepared cyclic DTPA-dianhydride. The best results of the conjugation were obtained by the addition of 1 mg of a gonadorelin to a glass tube pre-coated with DTPA-dianhydride (0.33 mg) at 25 °C with continuous mild stirring for 1 hour. Radio thin layer chromatography showed an overall radiochemical purity of >90% at optimized conditions after labeling. HPLC showed a radiochemical purity more than 95% (specific activity = 400–450 GBq/M). The stability of the radioconjugate was tested in presence of human serum at 37 °C. Preliminary in vivo studies in normal rats were performed to determine the biodistribution of the conjugate up to 48 hours. The breast and ovaries uptakes were significantly high in first 15-minute post injection which is in agreement with the other reports regarding the presence of specific GnRH receptors. This tracer can be used in detection of GnRH receptor biodistribution in various diseases and malignancies.     

Preparation and biodistribution of [67Ga]-DTPA-rituximab in normal rats

Rituximab was successively labeled with [⁶⁷Ga]-gallium chloride after residulation with freshly prepared cyclic DTPA-dianhydride. The best results of the conjugation were obtained by the addition of 1 ml of a rituximab pharmaceutical solution (5 mg/ml, in phosphate buffer, pH 8) to a glass tube pre-coated with DTPA-dianhydride (0.01 mg) at 25 °C with continuous mild stirring for 30 minutes. Radio thin-layer chromatography showed an overall radiochemical purity of 96–99% at optimized conditions (specific activity = 300–500 MBq/mg, labeling efficiency 77%). The final isotonic ⁶⁷Ga-DTPA-rituximab complex was checked by gel electrophoresis for radiolysis control. Radio-TLC was performed to ensure the formation of only one species, followed by filtration through a 0.22 μm filter. Preliminary in vivo studies in normal rat model was performed to determine the biodistribution of the radioimmunoconjugate up to 6 hours.     

Uptake of 67Ga into the rat liver after treatment with thioacetamide

67Ga uptake of the liver began to elevate from the 1st day and reached a maximum at the 2nd day of treatment with thioacetamide (TIAA). Incorporation of 3H-thymidine into the liver DNA fraction was reached a maximum at the 1.5th day, and the value was 5.7 times of the control. The uronic acid content and 35S incorporation in the 1.2 M NaCl-soluble fraction which contained predominantly heparan sulfate (HS), were both peaked at the 2nd day. These patterns were in good agreement with that of 67Ga uptakes in the liver treated with TIAA. Pretreatment of aminoacetonitrile, an inhibitor of fibrosis, was effective in lowering the elevated uptake of 67Ga in TIAA-treated rat liver. Uptake of the 67Ga in the TIAA-treated liver was also inhibited when they were treated with cycloheximide, an inhibitor of protein synthesis. On the other hand no significant inhibition was observed in the cytosine arabinoside-treated-TIAA rats. These results suggest that HS may be involved in the 67Ga uptake in damaged liver, and that relation between 67Ga uptake and cell proliferation is secondary.     

Effect of gallium nitrate on the in vivo distribution of 67Ga in rats bearing inflammatory lesions

Effect of gallium nitrate on the pharmacokinetics and tissue accumulation of 67Ga was investigated in rats bearing turpentine oil-induced abscess. Gallium nitrate accelerated the blood disappearance of 67Ga, but this effect was less potent than that of ferric nitrate. The accumulation of 67Ga in liver was significantly lowered by gallium nitrate, but no significant decrease of 67Ga accumulation in abscess was observed. On the other hand, 67Ga accumulation in bone was slightly facilitated by gallium nitrate. Ferric nitrate exerted a similar effect on tissue accumulation of 67Ga as gallium nitrate.     

The influences of dexamethasone and indomethacin on 67Ga uptake by normal tissues

Dexamethasone (DEX) increased 67Ga uptake by the liver and spleen at 4, 8, and even 24 h after the injection of 67Ga. These results showed that DEX influenced 67Ga accumulation as well as the initial entry of 67Ga in the liver and spleen. On the other hand, indomethacin (IM) decreased 67Ga uptake by the liver and spleen at 4 h after the injection of 67Ga but did not influence the uptake at 8 or 24 h after the injection of 67Ga. Moreover, DEX or IM little influenced 67Ga uptake by the kidney and muscle. These results suggest that the influence of DEX or IM on 67Ga uptake or accumulation is specific for the liver and spleen.     

Investigation of red blood cell fractionation by gravitational field-flow fractionation.

Gravitational field-flow fractionation is used for the separation of particles according to their sizes in the range 1-100 microns: larger particles elute before smaller ones. This phenomenon can be explained as a result of the steric exclusion of the particles from the vicinity of the channel walls, and/or hydrodynamic effects supposedly associated with the inertia of the liquid. The method was used for the investigation of red blood cells. The dependence of the retention ratio on the flow-rate, sample volume, concentration of blood and relaxation time was studied. Analysis of fifteen individual fractions by Coulter counter and reinjection of three other fractions were studied in order to verify fractionation of red blood cells.     

Molecular weight distribution of cellulose by fractionation in cadoxen solutions

The fractionation of cellulose in cadoxen solutions has been carried out by precipitation with aqueous propanol. The reproducibility of the method has been tested by means of parallel fractionations, and shown to be good, for both research and routine work. The fractionation data have been analysed using Beall and Schulz methods, and the results compared.     

Chemical fractionation of a fly ash sample by a sequential leaching method

A five-stage sequential leaching procedure was optimized for the analysis of the fly ash sample, CW6, as a candidate reference material. The distribution of particulate elements was achieved for Cd, Cr, Cu, Pb, Zn, and V into different fractions: (1) exchangeable, (2) bound to carbonate, (3) bound to Fe/Mn oxides, (4) bound to sulfide compounds, and (5) acid soluble, residual fraction. The leachability of the metals proved to be different, so various distribution patterns have been achieved. The results of the total elemental analysis and the sequential leaching method were compared and a good agreement was found. The uncertainty of the leaching method is reasonable, even when experimental parameters are strictly fixed and the analysis is quite tedious. The ratio of environmentally mobile fractions was compared to that from the conventional test method and a reasonable conformity has been found. This characterization method can be used to interpret the leaching behavior of element species and mode of binding to the matrix. Using the optimized sequential procedure, a new aspect can be interpreted to understand the behavior of toxic elements released from fly ashes into nature.     

Relation between 67Ga uptake and the stage of inflammation induced by turpentine oil in rats

For the establishment of the experimental system to judge easily the effect of anti-inflammatory drug, 67Ga-citrate was used. The weight of granuloma tissues induced by inflammable agent, turpentine oil, gradually increased and reached a maximum at 6 days after the administration of turpentine oil. Gallium-67 accumulation in the inflammatory lesions showed also a maximum at 6 days after that. Both patterns were closely similar each other. These results showed that the processes and/or stages of inflammation could be indicated by the pattern of 67Ga uptake.     

Study on chemical separation of67Ga VIAnatZn(p,xn) reaction

A potential⁶⁸Ge/⁶⁸Ga generator system has orginally been established by using adsorption chromatography on inorganic adsorbent SiO₂. This type of generator delivers 90% of⁶⁸Ga with the breakthrough levels of⁶⁸Ge lower than 10^–3% per 10 ml of collection volume and readily provides tracer for this experimental study. Three routes for the separation of⁶⁷Ga from Zn target, including solvent extraction with allylether and cation exchange with Dowex 50W-×8 as well as anion exchange with AG1-×8, have been investigated and compared. The simulated experiments were performed with synthetic solutions containing appropriate amounts of Zn, the possible impurities, Fe, Cu and their radioactive tracers. The results show that a single stage allylether solvent extraction permits an extremely high recovery yield of 99% of⁶⁷Ga with a desired radionuclidic purity and almost complete removal of the chemical impurities. By a combination of cation-exchange separation followed with allylether extraction, a slightly lower yield (89%) but highest purity of the product can be obtained. The anion exchange process is of less interest due to its low recovery of⁶⁷Ga and poor decontamination of the impurities.     

A case of parathyroid carcinoma visualized by 67Ga citrate and 201Tl chloride scintigraphy

Both 67Ga citrate and 201Tl chloride accumulated in a parathyroid tumor of a 62 year-old woman with primary hyperparathyroidism. Histological studies disclosed that the tumor was a parathyroid carcinoma. The use of both tumor scanning agents, 67Ga citrate and 201Tl chloride to visualize parathyroid carcinoma in a patient with primary hyperparathyroidism has not been reported as far as we could determine.     

Standardless method for quantitative particle-size distribution studies by gravitational field-flow fractionation. Application to silica particles

Summary Gravitational field-flow fractionation is a separative analytical technique which has already proved suitable for quantitative particle-size distribution analysis. One of the most attractive aspects of the technique is that it can allow for direct conversion of fractograms into size distributions of the samples, although retention exhibits substantial dependence on flow rate, compared to other field-flow fractionation methods. It is shown here that conversion of fractograms into quantitative, size-distribution profiles of micron-sized silica particles is possible through gravitational field-flow fractionation in standardless mode. Standardless means that the conversion of fractograms is performed by single-run analysis because all the parameters necessary for the calculations can be obtained, from sample specifications and previous instrumental calibration, by means of semiempirical models. Work partially presented at FFF’98-7^th International Symposium on Field-Flow Fractionation, Salt Lake City, Utah (USA), February 8–11, 1998     

Characterization of winemaking yeast by cell number-size distribution analysis through flow field-flow fractionation with multi-wavelength turbidimetric detection

Yeasts are widely used in several areas of food industry, e.g. baking, beer brewing, and wine production. Interest in new analytical methods for quality control and characterization of yeast cells is thus increasing. The biophysical properties of yeast cells, among which cell size, are related to yeast cell capabilities to produce primary and secondary metabolites during the fermentation process. Biophysical properties of winemaking yeast strains can be screened by field-flow fractionation (FFF). In this work we present the use of flow FFF (FlFFF) with turbidimetric multi-wavelength detection for the number-size distribution analysis of different commercial winemaking yeast varieties. The use of a diode-array detector allows to apply to dispersed samples like yeast cells the recently developed method for number-size (or mass-size) analysis in flow-assisted separation techniques. Results for six commercial winemaking yeast strains are compared with data obtained by a standard method for cell sizing (Coulter counter). The method here proposed gives, at short analysis time, accurate information on the number of cells of a given size, and information on the total number of cells.     

Binding of 67 Ga and 59 Fe to ferritin or transferrin

The bindings of 67Ga and 59Fe to ferritin or transferrin in vitro has been investigated. Affinity constants have been measured using the equilibrium dialysis, and the results have been obtained as follows: 1 Apo-ferritin could not bind to 67Ga until it was transformed into ferritin in presence of Fe-citrate. On the contrary, the affinity of 67Ga to ferritin was reduced when Fe was released from ferritin; thus indicating that Fe-core has been required for the binding of 67Ga to ferritin. 2 Binding of 67Ga to ferritin was inhibited with apo-transferrin, and this was also shown in the case of 59Fe. In the presence of NaHCO3 or citrate, more remarkable inhibitions were observed. NaHCO3 or citrate was found to give a synergistic effect on the binding of 67Ga to transferrin, as well as Fe-transferrin. Therefore, both 67Ga and 59Fe could not bind to ferritin in the state of 67Ga- or 59Fe-transferrin. 3 The release of 59Fe from 59Fe-transferrin was enhanced with adenosine triphosphate (ATP), citrate, or ascorbic acid, while any of these reagents did not affect the release of 67Ga from 67Ga-transferrin. The comparison of 59Fe and 67Ga through their bindings to ferritin or transferrin has suggested one of points to distinguish 67Ga from 59Fe in the cell.     

Separation and composition distribution determination of triblock copolymers by thermal field-flow fractionation

Thermal field-flow fractionation (ThFFF) is used to separate a linear triblock copolymer of polystyrene, poly(tert-butyl acrylate), and poly(methyl methacrylate) by composition. Fractions were collected and subjected to off-line NMR analysis. The resultant mole fraction versus retention time plots for each of the three polymer components confirmed the success of the separation and yielded the composition distribution of the copolymer. The composition distribution was also obtained using a second approach that involved solving a series of equations comprised of polymer thermal diffusion coefficients and quasi-elastic light scattering, differential refractometry, and UV detector responses. Both sets of data showed similar trends of composition variations in each polymer component as a function of retention time. However, discrepancies were observed in the mole fraction values. The ability to compositionally separate and to determine composition distribution of copolymers is important as demonstrated by the presence of diblock impurities in the ThFFF with off-line NMR results.     

Mechanism of 67Ga uptake by an experimental abscess--permeability of plasma from blood vessels in abscessed tissue

In the previous paper, we reported that 67Ga was accumulated in abscess and uptake rate of 67Ga in abscess increased with time after the injection of 67Ga-citrate. The present study was undertaken to elucidate the influence of blood flow on the accumulation of 67Ga in abscess. Five days after subcutaneous injection of 0.2 ml of turpentine to the rats, 131I-human serum albumin (HSA) was injected intravenously to the rats. At an appropriate time after the injection (10 min to 6 days), uptake rates of 131I-HSA in abscess and normal tissues were measured. Similarly, 51Cr-red blood cells (RBC) were injected intravenously to the above rats and the uptake rates of 51Cr-RBC were also measured. One, three, and 24 hours after injection of 131I-HSA, the uptake rates of 131I-HSA in abscess were 1.32 %dose/g, 1.84 %dose/g, and 0.82 %dose/g, respectively. However, the uptake rates of 51Cr-RBC in abscess was very small, and the value was 0.14 %dose/g at 24 hours after the injection. In the case of abscess, blood in the tissue fluid was very little, but the permeability of 131I-HSA from the blood vessel in the tissue was much larger than that of normal tissues. From these facts, it was deduced that the accelerated permeability caused the abscess accumulation of 67Ga.     

Determination of molecular weight distribution of cellulose by conversion into tricarbanilate and fractionation

Two samples of cellulose (molecular weight 2.97 × 10⁵ and 1.25 × 10⁵) were transformed into carbanilates (CTC) which were then fractionated by the elution method at a constant composition of the acetone-water elution mixture with the column temperature gradually increasing from ?30°C to 30°C, and by the GPC method in acetone and tetrahydrofuran. Tetrahydrofuran appeared to be a more suitable solvent. The molecular weights of fractions obtained by the elution fractionation were determined by the light-scattering method in tetrahydrofuran. The width of fractions was determined by the GPC method (average M _w/M _n = 1.37); the [η] values and the Mark-Houwink constants (K = 5.3 × 10^-3, a = 0.84) for tetrahydrofuran at 25°C were determined. The calibration curve for the GP method was constructed by means of the fractions thus obtained; it was demonstrated that the universal calibration curve according to Benoit can also be used. It was demonstrated that the molecular weight distribution of cellulose can be conveniently determined by conversion into CTC followed either by the elution fractionation (for preparative purposes) or by fractionation by the GPC method (for analytical purposes).