International journal of nuclear medicine and biology最新文献

A new bifunctional chelating agent, p-carboxyethylphenylglyoxal-di(N-methylthiosemicarbazone) (CE-DTS), containing a di(N-methylthiosemicarbazone) as the technetium coordinating site and an aralkyl carboxylate site for the protein conjugation was synthesized. Coupling to human serum albumin (HSA), selected as a model protein was carried out by the phosphorylazide method using diphenylphosphoryl azide (DPPA). The conjugation level of CE-DTS to HSA played a critical role in its biological evaluation. A ^99mTc-CE-DTS-HSA with high in vivo stability was obtained when CE-DTS was coupled to HSA at 1:1 molar ratio. This compound showed similar in vivo stability to ¹³¹I labeled HSA in mice and rabbits.

As Zn is closely associated with the exocrine and endocrine functions of the pancreas, exploitation of Zn metabolism for anatomical and functional diagnosis was conceived, namely with the recent availability of positron emitting ⁶²Zn (t½ = 9 h). In the present paper, response changes in Zn biodistribution (mice) and Zn excretion through the pancreatic duct (rats) due to the stimulation of gastro-intestinal hormones like secretin, CCK-PZ (exocrine stimulation) and glucose (endocrine stimulation) were studied. Under these stimuli, the pancreatic secretion of radioactive Zn through cannulated pancreatic duct showed increased Zn secretion only under the CCK-PZ effect, 3 h post ⁶⁵Zn (t½ = 270 d) injection. Tissue biodistribution in mice pre-injected with ⁶⁵Zn showed pancreas specific decrease of radioactive Zn whenever a gastro-intestinal hormone was post-administered, whereas the glucose effect was negligible. Thus, the effective mobilization of the injected radioactive Zn, upon exocrine stimulation, represented by CCK-PZ, favored the exploration of a functional study of the pancreas with the positron computed tomograph (PCT) using short lived nuclide labeled ⁶²Zn-EDDA in dog. Evidence of the applicability of this system in regional function studies of the pancreas was obtained. Demonstration of Zn participation in the exocrine function of the pancreas in-vivo holds considerable promise for diagnosis of pancreatic diseases.

As a basic structure of a bifunctional radiopharmaceutical (BR), dithiosemicarbazone (DTS) enables the formation of a small conjugated chelating ring with divalent metals (Cu²⁺, Zn²⁺, Ni²⁺), yielding stable and compact complexes.

In the development of a neutral and compact monomelic DTS complex of technetium (^99mTc), a DTS containing ligand, kethoxal-bis(thiosemicarbazone) (KTS) was selected. A well known monomelic Cu-KTS complex (or ⁶⁴Cu-KTS) is taken as a model compound, and in vitro (TLC, EP, HPLC) and in vivo (mice biodistribution) studies were compared. Using the stannous chloride method, under conditions to avoid the hydrolytic polynucleation of technetium, a good yield of ^99mTc-KTS with characteristics resembling the non-charged, compact and stable Cu-KTS is obtained, in in vitro as well as in vivo studies. The importance of DTS as the constituent of a BR is discussed.

The chelating agents oxine, acetylacetone, tropolone, and 2-mercaptopyridine 1-oxide were analysed for their suitability in labeling the bacterium Erysipelothrix rhusiopathiae (E.r.), strain BIO, with ¹¹¹In and ⁶⁷Ga. The labeling conditions were improved. The bactericidal activity of the labeling process was investigated. The different chelates did not result in a significant difference in labeling yield. The addition of 0.01% detergent to the labeling buffer doubled the labeling yield up to 45%. Labeled bacteria were injected intravenously into rats. The percentage organ distribution was determined and compared with a control group.