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Journal of Thermal Analysis and Calorimetry
Authors: J. R. Azevedo, R. H. Sizilio, M. B. Brito, A. M. B. Costa, M. R. Serafini, A. A. S. Araújo, M. R. V. Santos, A. A. M. Lira, and R. S. Nunes

applied to avoid the possible toxicity of other crosslinkers agents, it can interact with the cationic chitosan by electrostatic forces. Numerous studies describe the use of nanoparticles as a way to encapsulating insulin in order to enhance or

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Abstract  

In this article we studied the dynamic dissociation constant (k d) of 99Mo complexed with insulin molecule at various pH. The k d values were determined by dialysis technique against deionised water. The T 1/2 of the molybdenum–insulin complexes were found to be 6.41, 5.25 and 3.5 h at pH 5, 6 and 7 respectively. The half-lives indicate that insulin may act as good carrier of 99Mo to the intestine and may be useful in the field of nuclear medicine.

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Abstract  

In order to target insulin receptors in various diabetic and insulinoma conditions, human recombinant insulin was successively labeled with [111In]-indium chloride after conjugation with freshly prepared cyclic DTPA-dianhydride (ccDTPA). The best results of the conjugation were obtained by addition of 0.5 mL of an insulin 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 (RTLC), instant thin layer chromatography (ITLC) and high performance liquid chromatography (HPLC) have shown an overall radiochemical purity of higher than 93% at optimized conditions (specific activity = 550–750 MBq/mg, radiochemical yield =81%). The white blood cell labeling capacity of the tracer was determined up to 4 hours at 37 °C. Preliminary in vivo studies in normal rat model was performed to determine the biodistribution of the radiotracer up to 48 hours. It showed a high liver and spleen uptake of the tracer which is consistent with other reported radiolabeled insulins. SPECT images have also shown high liver accumulation of the tracer.

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Abstract  

A first attempt to label insulin, a small protein with significant affinity to tumors with the α-emitter 211At was performed by an indirect method using N-succinimidyl 5-(tributylstannyl)-3-pyridinecarboxylate (SPC) as a bi-functional linker, and the stability of the conjugated insulin (211At-insulin) was evaluated in vitro and in vivo. SPC was synthesized by using 5-bromonicotinic acid as the starting material. With this bi-functional linker, insulin was conjugated with 211At in a labeling yield of 30–40%, with radiochemical purity of more than 98%. After 24 hours at room temperature, the radiochemical purity was still more than 95%, implying that 211At-insulin is fairly stable in vitro. Biodistribution of 211At-insulin was investigated in NIH strain mice. 211At accumulated rapidly in the liver post injection, with the maximum uptake of 4.29%I.D/g at 30 minutes, and was mainly excreted by kidney. More importantly, 211At-insulin uptake in some key organs or tissues, especially in thyriod, stomach, lung and spleen, was much less than that of free astatide (211At). This result indicated that 211At-insulin has considerable stability in vivo as well as in vitro.

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Summary  

Insulin receptors are overexpressed on a number of human tumors, leading to significant affinity of insulin to these tumors. It is appealing to receptor-targeted radiotherapy for malignant tumors if insulin is labeled with suitable radionuclide. In this paper, N-succinimidyl 5-(tributylstannyl)-3-pyridinecarboxylate (SPC), a potential bi-functional linker for radioiodination of proteins or peptides, was synthesizedby using 5-bromonicotinic acid as the starting material. Then, with this bi-functional linker, insulin was conjugated with 131I, and the tissue distribution of the labeled insulin (131I-SIPC-insulin) in normal mice was investigated. The results showed that insulin  could be conjugated with131I using SPC as the linker  in a labeling yield of40-58%, and with radiochemical purity of more than 98% after purification bySephadexÔG-10. Even kept at room temperature for 72 hours, the radiochemical purity of 131I-SIPC-insulin was still more than 97%, implying that the conjugated insulin was constantly stable in vitro.Meanwhile, in order to evaluate the in vivo stability of the conjugated compounds, insulin was also labeled with 131I by a direct method using chloramine-T (Ch-T) as the electrophilic agents.Biodistribution of131I-SIPC-insulinin micesuggested that 131I could clear rapidly from the blood,mainly excreted by kidney. However, 131I uptake of mice with131I-SIPC-insulin in some key organs, especially in thyroid and stomach, were much less (150 or 30 times) than that with the direct labeled insulin (131I-insulin). Additionally, it was noted that 131I-SIPC-insulin hasmuch betterinvivo stability than131I-insulin.

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Introduction A variety of vanadium chelate complexes have been shown to have insulin-mimetic properties in animal model and cell culture systems, thus these compounds have great potential for the pharmacotherapy of diabetes [ 1

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Introduction Nowadays many studies concerning vanadium complexes are directed through discovery of new species able either activates the insulin or even supply the insulin in human metabolism [ 1 ]. The problems that should be

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Journal of Thermal Analysis and Calorimetry
Authors: Mihaela Badea, Rodica Olar, Valentina Uivarosi, Dana Marinescu, Victoria Aldea, Stefania Felicia Barbuceanu, and George Mihai Nitulescu

The new complexes of oxovanadium (IV) with ligands belong to a class of coordination compounds of current interest for their insulin-mimetic and antitumoral activity have been synthesized and characterized by analytical and spectral investigations. A

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Abstract  

Radioiodinated insulin and thyroid stimulating hormones were prepared using 1,3,4,6-tetrachloro-3, 6-diphenylglycouril (Iodogen). Conditions of iodination like concentration of iodogen, reaction time, etc., were optimized to get maximum yield. Stability studies of iodogen coated tubes were carried out over a period of time. The dependence of iodination yield on varying amounts of activity and protein concentration were investigated. Iodination yield over a range of pH was also studied. The radiolabelled hormones prepared by this method were used in radioimmunoassay and were compared with tracers prepared by the Chloramine-T method.

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A series of new complexes of the type VO(OH)L·nH2O ((1) L: fisetin, n = 3; (2) L: quercetin, n = 2; (3) L: morin, n = 4) were synthesised and characterised by analytical as well as IR and electronic data. The modification evidenced in IR spectra was correlated with the presence of flavonoid as bidentate in all complexes. The electronic reflectance spectra showed the dd transition characteristic for the square-pyramidal stereochemistry of vanadium (IV) ion. The thermal analysis (TG, DTA) in synthetic air flow elucidated the composition and also the number and nature of the water molecules. The TG curves show three well-separated thermal events. The first corresponds to the water loss at lower temperatures, which is followed by flavonoid derivative decomposition and pyrolysis at higher temperatures. The final product is vanadium (V) oxide.

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