International journal of nuclear medicine and biology最新文献

A modified, simple and radiometric method for early detection of M. tuberculosis from sputum samples has been developed using a biphasic vial system for detection of ¹⁴CCO₂ produced by the metabolism of ¹⁴CU-acetate on glycerol-free Lowenstein-Jensen medium (LJM).

Of the 84 smear positive sputum samples examined, 85.7% and 86.9% o were scored positive by radiometric and visual methods respectively. The detection rates at 1st, 2nd and 3rd week of the test were 53.3%, 60.7% and 82.1% by radiometry and 1.2%, 11.9% and 54.8% by visual methods respectively.

The mean detection time was 10.7 days by the radiometric and 21.0 days by the visual method. An average replication time of primary culture from 54 sputum samples was 25.58 ± 6.92 h (range 10.0–39.1 h).

Highly purified high and low molecular weight urokinase (H-UK and L-UK) were labeled with ⁶⁷Ga using deferoxamine (DF) as a bifunctional chelating agent. The labeling efficiency was 91.7% for the H-UK, and 90.4% for the L-UK, respectively. The ⁶⁷Ga labeled UK (⁶⁷Ga-DF-UK) fully retained the enzymatic activity of the parent UK. Studies on the in vivo behavior of the ⁶⁷Ga labeled UK in rabbits showed a very rapid blood clearance with half-life of 4 min (⁶⁷Ga-DF-L-UK) to 8 min (⁶⁷Ga-DF-H-UK Studies carried out in rabbits with induced thrombi in the femoral vein showed thrombus-to-blood ⁶⁷Ga-DF-UK activity ratios, 2 h after injection, of 2.00–3.08 for the H-UK, and 0.84–1.65 for the L-UK, respectively, with thrombi aged 4 to 3 days. A dose effect of the ⁶⁷Ga-DF-H-UK on its thrombus accumulation was observed. Gel chromatographic analysis of plasma samples withdrawn from those animals injected with this radiopharmaceutical revealed a reduction of the ⁶⁷Ga-DF-UK effectiveness due to complexation with protein inhibitors. This led to formation of high molecular weight complexes which was reflected in the very fast blood clearance. Its implication in thrombus accumulation is discussed. In conclusion, usefulness of DF for labeling UK with ⁶⁷Ga or ⁶⁸Ga with no alteration of UK enzymatic properties was demonstrated. The use of ⁶⁷Ga-DF-UK as a diagnostic or therapeutic radiopharmaceutical is promising.

Transferrin is essential for the entry of iron into cells, but whether the entire iron-transferrin complex or only the iron enter is not known. Separation of the cellular from the interparticulate radioactivity is a common problem with such studies. By pelleting cells under oil, we have made precise measurements of the uptake capacity for ⁵⁹Fe of mouse lymphoma RI cells. At 37°C an 18-fold concentration of iron was observed within 30 min; at 0°C this value was about 3-fold. At 37°C a maximus of 18,000 molecules of ¹²⁵I-labelled Fe-transferrin were bound to each cell; this was reduced by about half at 0°C. At 37°C about 10,000–12,000 binding sites for ¹²⁵I-apotransferrin were detected on each cell. From our data we conclude that although essential enters RI cells. It is possible that iron is actively transported and that the receptor population is heterogenous.

In an attempt to compare the efficacy of various 5-fluorouracil (5-FU) regimens, we studied the kinetics of ¹⁸F-labeled and unlabeled 5-FU in rats. ¹⁸F-5-FU was synthesized in our laboratory and was administered in tracer doses to Fischer rats bearing either the 13762 or the R3230 mammary adenocarcinoma, and to Sprague-Dawley rats bearing the Walker-256 carcinosarcoma, with or without pre-treatment with a therapeutic dose of unlabeled 5-FU. In addition, the non-radioactive 5-FU was administered to control rats of both strains. All animals were followed for 70 min either by measuring their ¹⁸F blood levels continuously using an extracorporeal blood-loop, or by determining their 5-FU blood levels at discrete time intervals. The biphasic kinetic profile was characterized by determining α and β rate constants and their corresponding half-lives. Differences in ¹⁸F elimination, as measured by the area under the curve during the elimination phase, were observed between the pre-treated 13762-bearing rats and the untreated group bearing the same tumor. as well as the pre-treated non-tumored controls and both W-256-bearing groups. Such differences could reveal changes in the ability of those rats to metabolize 5-FU, and hence correlate to the level of active metabolite(s) available to their tumor sites.